dvc status error with S3 output
DVC version 0.17.1, installed with pip.

Running `dvc status` shows
```
Failed to obtain data status: 'OutputS3' object has no attribute 'rel_path'
```
and nothing else (e.g. files that are not output to S3)

My .dvc/config:
```
['remote "data"']
url = s3://xxxxx/data
[core]
remote = data
['remote "s3cache"']
url = s3://xxxxx/cache
[cache]
s3 = s3cache
```
diff --git a/dvc/config.py b/dvc/config.py
index 18f5ddd61..352065fe3 100644
--- a/dvc/config.py
+++ b/dvc/config.py
@@ -10,8 +10,9 @@ from dvc.exceptions import DvcException
 
 class ConfigError(DvcException):
     """ DVC config exception """
-    def __init__(self, ex=None):
-        super(ConfigError, self).__init__('Config file error', ex)
+    def __init__(self, msg, ex=None):
+        super(ConfigError, self).__init__('Config file error: {}'.format(msg),
+                                          ex)
 
 
 def supported_url(url):
diff --git a/dvc/dependency/base.py b/dvc/dependency/base.py
index 96f37a60f..970fc540a 100644
--- a/dvc/dependency/base.py
+++ b/dvc/dependency/base.py
@@ -59,7 +59,11 @@ class DependencyBase(object):
     def status(self):
         if self.changed():
             # FIXME better msgs
-            return {self.rel_path: 'changed'}
+            if self.path_info['scheme'] == 'local':
+                p = self.rel_path
+            else:
+                p = self.path
+            return {p: 'changed'}
         return {}
 
     def save(self):
diff --git a/tests/test_repro.py b/tests/test_repro.py
index ad5147cea..f5af30043 100644
--- a/tests/test_repro.py
+++ b/tests/test_repro.py
@@ -380,6 +380,8 @@ class TestReproExternalBase(TestDvc):
 
         sleep()
 
+        self.dvc.status()
+
         stages = self.dvc.reproduce(import_stage.path)
         self.assertEqual(len(stages), 1)
         self.assertTrue(os.path.exists('import'))
['tests/test_repro.py', 'dvc/dependency/base.py', 'dvc/config.py']