resmgr: download --overwrite does not work
I accidentally ran `calamari-predict` from the top-level (instead of a sub-venv), which tried to update my GT4HistOCR model to the more recent TF – overwriting the checkpoint JSON.

Now, I tried to download that model again:
```shell
ocrd resmgr download --overwrite ocrd-calamari-recognize qurator-gt4histocr-1.0
INFO ocrd.cli.resmgr - Downloading resource {'url': 'https://qurator-data.de/calamari-models/GT4HistOCR/2019-12-11T11_10+0100/model.tar.xz', 'type': 'tarball', 'name': 'qurator-gt4histocr-1.0', 'description': 'Calamari model trained with GT4HistOCR', 'size': 90275264, 'path_in_archive': '.', 'version_range': '>= 1.0.0', 'parameter_usage': 'as-is'}
INFO ocrd.resource_manager._download_impl - Downloading https://qurator-data.de/calamari-models/GT4HistOCR/2019-12-11T11_10+0100/model.tar.xz to download.tar.xx
  [####################################]  100%          INFO ocrd.resource_manager.download - Extracting tarball
INFO ocrd.resource_manager.download - Copying '.' from tarball to /.local/share/ocrd-resources/ocrd-calamari-recognize/qurator-gt4histocr-1.0

Traceback (most recent call last):
  File "/venv/bin/ocrd", line 8, in <module>
    sys.exit(cli())
  File "/venv/lib/python3.6/site-packages/click/core.py", line 829, in __call__
    return self.main(*args, **kwargs)
  File "/venv/lib/python3.6/site-packages/click/core.py", line 782, in main
    rv = self.invoke(ctx)
  File "/venv/lib/python3.6/site-packages/click/core.py", line 1259, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/venv/lib/python3.6/site-packages/click/core.py", line 1259, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/venv/lib/python3.6/site-packages/click/core.py", line 1066, in invoke
    return ctx.invoke(self.callback, **ctx.params)
  File "/venv/lib/python3.6/site-packages/click/core.py", line 610, in invoke
    return callback(*args, **kwargs)
  File "/venv/lib/python3.6/site-packages/ocrd/cli/resmgr.py", line 137, in download
    progress_cb=lambda delta: bar.update(delta)
  File "/venv/lib/python3.6/site-packages/ocrd/resource_manager.py", line 225, in download
    copytree(path_in_archive, str(fpath))
  File "/usr/lib/python3.6/shutil.py", line 321, in copytree
    os.makedirs(dst)
  File "/usr/lib/python3.6/os.py", line 220, in makedirs
    mkdir(name, mode)
FileExistsError: [Errno 17] File exists: '/.local/share/ocrd-resources/ocrd-calamari-recognize/qurator-gt4histocr-1.0'
```

Looks like `overwrite` is not implemented properly.
diff --git a/ocrd/ocrd/cli/resmgr.py b/ocrd/ocrd/cli/resmgr.py
index a2ddddf4..c41892a8 100644
--- a/ocrd/ocrd/cli/resmgr.py
+++ b/ocrd/ocrd/cli/resmgr.py
@@ -151,23 +151,26 @@ def download(any_url, no_dynamic, resource_type, path_in_archive, allow_uninstal
                 if not basedir:
                     basedir = resmgr.location_to_resource_dir('data')
 
-            with click.progressbar(length=resdict['size']) as bar:
-                fpath = resmgr.download(
-                    this_executable,
-                    resdict['url'],
-                    name=resdict['name'],
-                    resource_type=resdict.get('type', resource_type),
-                    path_in_archive=resdict.get('path_in_archive', path_in_archive),
-                    overwrite=overwrite,
-                    no_subdir=location in ['cwd', 'module'],
-                    basedir=basedir,
-                    progress_cb=lambda delta: bar.update(delta)
-                )
-            if registered == 'unregistered':
-                log.info("%s resource '%s' (%s) not a known resource, creating stub in %s'", this_executable, name, any_url, resmgr.user_list)
-                resmgr.add_to_user_database(this_executable, fpath, url=any_url)
-            resmgr.save_user_list()
-            log.info("Installed resource %s under %s", resdict['url'], fpath)
+            try:
+                with click.progressbar(length=resdict['size']) as bar:
+                    fpath = resmgr.download(
+                        this_executable,
+                        resdict['url'],
+                        name=resdict['name'],
+                        resource_type=resdict.get('type', resource_type),
+                        path_in_archive=resdict.get('path_in_archive', path_in_archive),
+                        overwrite=overwrite,
+                        no_subdir=location in ['cwd', 'module'],
+                        basedir=basedir,
+                        progress_cb=lambda delta: bar.update(delta)
+                    )
+                if registered == 'unregistered':
+                    log.info("%s resource '%s' (%s) not a known resource, creating stub in %s'", this_executable, name, any_url, resmgr.user_list)
+                    resmgr.add_to_user_database(this_executable, fpath, url=any_url)
+                resmgr.save_user_list()
+                log.info("Installed resource %s under %s", resdict['url'], fpath)
+            except FileExistsError as exc:
+                log.info(str(exc))
             log.info("Use in parameters as '%s'", resmgr.parameter_usage(resdict['name'], usage=resdict.get('parameter_usage', 'as-is')))
 
 @resmgr_cli.command('migrate')
diff --git a/ocrd/ocrd/resource_manager.py b/ocrd/ocrd/resource_manager.py
index dd1a3170..6ac6d26d 100644
--- a/ocrd/ocrd/resource_manager.py
+++ b/ocrd/ocrd/resource_manager.py
@@ -1,9 +1,10 @@
 from pathlib import Path
 from os.path import join
+from os import environ, listdir, getcwd, path, unlink
+from shutil import copytree, rmtree
 from json import loads
 from os import environ, listdir, getcwd, path
 from fnmatch import filter as apply_glob
-from shutil import copytree
 from datetime import datetime
 from tarfile import open as open_tarfile
 from urllib.parse import urlparse, unquote
@@ -232,7 +233,7 @@ class OcrdResourceManager():
             return Path(name).stem
         raise ValueError("No such usage '%s'" % usage)
 
-    def _download_impl(self, url, filename, progress_cb=None):
+    def _download_impl(self, url, filename, progress_cb=None, size=None):
         log = getLogger('ocrd.resource_manager._download_impl')
         log.info("Downloading %s to %s" % (url, filename))
         with open(filename, 'wb') as f:
@@ -293,9 +294,15 @@ class OcrdResourceManager():
             name = Path(unquote(url_parsed.path)).name
         fpath = Path(destdir, name)
         is_url = url.startswith('https://') or url.startswith('http://')
-        if fpath.exists() and not overwrite:
-            log.info("%s to be %s to %s which already exists and overwrite is False" % (url, 'downloaded' if is_url else 'copied', fpath))
-            return fpath
+        if fpath.exists():
+            if not overwrite:
+                raise FileExistsError("%s %s already exists but --overwrite is not set" % ('Directory' if fpath.is_dir() else 'File', fpath))
+            if fpath.is_dir():
+                log.info("Removing existing target directory {fpath}")
+                rmtree(str(fpath))
+            else:
+                log.info("Removing existing target file {fpath}")
+                unlink(str(fpath))
         destdir.mkdir(parents=True, exist_ok=True)
         if resource_type in ('file', 'directory'):
             if is_url:
@@ -313,7 +320,7 @@ class OcrdResourceManager():
                     log.info("Extracting archive to %s/out" % tempdir)
                     with open_tarfile('../download.tar.xx', 'r:*') as tar:
                         tar.extractall()
-                    log.info("Copying '%s' from archive to %s" % (path_in_archive, fpath))
+                    log.info("Copying '%s' from tarball to %s" % (path_in_archive, fpath))
                     copytree(path_in_archive, str(fpath))
         return fpath
 
diff --git a/tests/cli/test_resmgr.py b/tests/cli/test_resmgr.py
index 46f18336..6cec6225 100644
--- a/tests/cli/test_resmgr.py
+++ b/tests/cli/test_resmgr.py
@@ -8,10 +8,11 @@ from ocrd.cli.resmgr import resmgr_cli
 from ocrd.resource_manager import OcrdResourceManager
 
 runner = CliRunner()
-executable = 'ocrd-tesserocr-recognize'
+executable = 'ocrd-dummy'
 
 @fixture
 def mgr_with_tmp_path(tmp_path):
+    print(tmp_path)
     mgr = OcrdResourceManager(xdg_data_home=tmp_path, userdir=tmp_path, xdg_config_home=tmp_path)
     env = {'XDG_DATA_HOME': str(tmp_path), 'XDG_CONFIG_HOME': str(tmp_path)}
     return tmp_path, mgr, env
@@ -21,8 +22,8 @@ def test_url_tool_name_unregistered(mgr_with_tmp_path):
     We should add a test for the -n URL TOOL NAME use-case as well (both as an unregistered resource and as URL-override).
     """
     tmp_path, mgr, env = mgr_with_tmp_path
-    print(mgr.list_installed('ocrd-tesserocr-recognize')[0][1])
-    rsrcs_before = len(mgr.list_installed('ocrd-tesserocr-recognize')[0][1])
+    print(mgr.list_installed(executable)[0][1])
+    rsrcs_before = len(mgr.list_installed(executable)[0][1])
 
     # add an unregistered resource
     url = 'https://github.com/tesseract-ocr/tessdata_best/raw/main/dzo.traineddata'
@@ -30,7 +31,7 @@ def test_url_tool_name_unregistered(mgr_with_tmp_path):
     r = runner.invoke(resmgr_cli, ['download', '--allow-uninstalled', '--any-url', url, executable, name], env=env)
     mgr.load_resource_list(mgr.user_list)
 
-    rsrcs = mgr.list_installed('ocrd-tesserocr-recognize')[0][1]
+    rsrcs = mgr.list_installed(executable)[0][1]
     assert len(rsrcs) == rsrcs_before + 1
     assert rsrcs[0]['name'] == name
     assert rsrcs[0]['url'] == url
@@ -38,12 +39,13 @@ def test_url_tool_name_unregistered(mgr_with_tmp_path):
     # add resource with different URL but same name
     url2 = url.replace('dzo', 'bos')
     r = runner.invoke(resmgr_cli, ['download', '--allow-uninstalled', '--any-url', url2, executable, name], env=env)
-    assert 'already exists and overwrite is False' in r.output
+    assert 'already exists but --overwrite is not set' in r.output
     r = runner.invoke(resmgr_cli, ['download', '--overwrite', '--allow-uninstalled', '--any-url', url2, executable, name], env=env)
-    assert 'already exists and overwrite is False' not in r.output
+    assert 'already exists but --overwrite is not set' not in r.output
+
     mgr.load_resource_list(mgr.user_list)
 
-    rsrcs = mgr.list_installed('ocrd-tesserocr-recognize')[0][1]
+    rsrcs = mgr.list_installed(executable)[0][1]
     print(rsrcs)
     assert len(rsrcs) == rsrcs_before + 1
     assert rsrcs[0]['name'] == name
@@ -73,3 +75,18 @@ def test_directory_copy(mgr_with_tmp_path):
         assert not r.exception
         assert Path(mgr_path / 'ocrd-resources' / proc).exists()
         assert directory_size(mgr_path / 'ocrd-resources' / proc /  res_name) == 30
+
+        r = runner.invoke(
+            resmgr_cli,
+            ['download', '--allow-uninstalled', '--any-url', tmp_path, proc, res_name],
+            env=env,
+            catch_exceptions=False
+        )
+        assert 'already exists but --overwrite is not set' in r.output
+        r = runner.invoke(
+            resmgr_cli,
+            ['download', '--overwrite', '--allow-uninstalled', '--any-url', tmp_path, proc, res_name],
+            env=env,
+            catch_exceptions=False
+        )
+        assert 'already exists but --overwrite is not set' not in r.output
diff --git a/tests/test_resource_manager.py b/tests/test_resource_manager.py
index f889a4ab..6d34fa8d 100644
--- a/tests/test_resource_manager.py
+++ b/tests/test_resource_manager.py
@@ -32,7 +32,7 @@ def test_resources_manager_config_default(monkeypatch, tmp_path):
     assert mgr.add_to_user_database('ocrd-foo', f)
     # pdb.set_trace()
 
-    mgr.list_installed()
+    mgr.list_installed('ocrd-foo')
     proc = 'ocrd-tesserocr-recognize'
     # TODO mock request
     fpath = mgr.download(proc, CONST_RESOURCE_URL_LAYOUT, mgr.location_to_resource_dir('data'))
@@ -55,7 +55,7 @@ def test_resources_manager_from_environment(tmp_path, monkeypatch):
     assert f.exists()
     assert f == mgr.user_list
     assert mgr.add_to_user_database('ocrd-foo', f)
-    mgr.list_installed()
+    mgr.list_installed('ocrd-foo')
     proc = 'ocrd-tesserocr-recognize'
     fpath = mgr.download(proc, CONST_RESOURCE_URL_LAYOUT, mgr.location_to_resource_dir('data'))
     assert fpath.exists()
@@ -66,14 +66,14 @@ def test_resources_manager_from_environment(tmp_path, monkeypatch):
 def test_resources_manager_config_explicite(tmp_path):
 
     # act
-    mgr = OcrdResourceManager(xdg_config_home=str(tmp_path))
+    mgr = OcrdResourceManager(xdg_config_home=str(tmp_path / 'config'), xdg_data_home=str(tmp_path / 'data'))
 
     # assert
-    f = tmp_path / 'ocrd' / CONST_RESOURCE_YML
+    f = tmp_path / 'config' / 'ocrd' / CONST_RESOURCE_YML
     assert f.exists()
     assert f == mgr.user_list
     assert mgr.add_to_user_database('ocrd-foo', f)
-    mgr.list_installed()
+    mgr.list_installed(executable='ocrd-foo')
     proc = 'ocrd-tesserocr-recognize'
     fpath = mgr.download(proc, CONST_RESOURCE_URL_LAYOUT, mgr.location_to_resource_dir('data'))
     assert fpath.exists()
['tests/cli/test_resmgr.py', 'ocrd/ocrd/resource_manager.py', 'ocrd/ocrd/cli/resmgr.py', 'tests/test_resource_manager.py']