Closes https://github.com/pyodide/pyodide/issues/604

This creates an installable `pyodide-build` Python package that we can also upload to PyPi under https://pypi.org/project/pyodide-build/ (currently uploaded the dev version to reserve the name).

There is also the identically named `pyodide-build` CLI command which replaces `bin/pyodide`.

The short term goals is to use fewer hacks with `PATH` and `PYTHONPATH`. Long term goal make it a user facing interface for building packages instead of the Makefile.
Create an installable pyodide-build package. Closes https://github.com/pyodide/pyodide/issues/604

This creates an installable `pyodide-build` Python package that we can also upload to PyPi under https://pypi.org/project/pyodide-build/ (currently uploaded the dev version to reserve the name).

There is also the identically named `pyodide-build` CLI command which replaces `bin/pyodide`.

The short term goals is to use fewer hacks with `PATH` and `PYTHONPATH`. Long term goal make it a user facing interface for building packages instead of the Makefile.
This fix for Python 3.8 warnings is already applied in upstream and
should probably be removed after next mpmath release.

diff --git a/mpmath/ctx_mp_python.py b/mpmath/ctx_mp_python.py
--- a/mpmath/ctx_mp_python.py
+++ b/mpmath/ctx_mp_python.py
@@ -889,7 +889,7 @@ def fsum(ctx, terms, absolute=False, squared=False):
             s = ctx.make_mpc((s, mpf_sum(imag, prec, rnd)))
         else:
             s = ctx.make_mpf(s)
-        if other is 0:
+        if other == 0:
             return s
         else:
             return s + other
@@ -983,7 +983,7 @@ def fdot(ctx, A, B=None, conjugate=False):
             s = ctx.make_mpc((s, mpf_sum(imag, prec, rnd)))
         else:
             s = ctx.make_mpf(s)
-        if other is 0:
+        if other == 0:
             return s
         else:
             return s + other

This fix for Python 3.8 warnings is already applied in upstream and
should probably be removed after next mpmath release.

diff --git a/mpmath/ctx_mp_python.py b/mpmath/ctx_mp_python.py
--- a/mpmath/ctx_mp_python.py
+++ b/mpmath/ctx_mp_python.py
@@ -889,7 +889,7 @@ def fsum(ctx, terms, absolute=False, squared=False):
             s = ctx.make_mpc((s, mpf_sum(imag, prec, rnd)))
         else:
             s = ctx.make_mpf(s)
-        if other is 0:
+        if other == 0:
             return s
         else:
             return s + other
@@ -983,7 +983,7 @@ def fdot(ctx, A, B=None, conjugate=False):
             s = ctx.make_mpc((s, mpf_sum(imag, prec, rnd)))
         else:
             s = ctx.make_mpf(s)
-        if other is 0:
+        if other == 0:
             return s
         else:
             return s + other
