Summary:
Solves issues below:
```
hgext/backups.py:18:1: F811 redefinition of unused 'registrar' from line 17
hgext/catnotate.py:1:1: F811 redefinition of unused 'util' from line 1
hgext/remotenames.py:57:5: F811 redefinition of unused 'registrar' from line 34
hgsubversion/setup.py:103:5: F401 'mercurial' imported but unused
hgsubversion/setup.py:109:5: F401 'hgsubversion.svnwrap.svn_swig_wrapper' imported but unused
i18n/polib.py:1281:29: F841 local variable 'exc' is assigned to but never used (Python 2)
i18n/polib.py:1427:13: F841 local variable 'typ' is assigned to but never used
i18n/polib.py:28:1: F401 'sys' imported but unused
mercurial/manifest.py:411:5: F811 redefinition of unused '_lazymanifest' from line 168
mercurial/posix.py:419:5: F811 redefinition of unused 'normcasefallback' from line 362
mercurial/posix.py:425:5: F811 redefinition of unused 'checkexec' from line 167
mercurial/posix.py:431:5: F811 redefinition of unused 'checklink' from line 234
mercurial/pycompat.py:29:5: F401 'http.cookiejar as cookielib' imported but unused
mercurial/pycompat.py:30:5: F401 'http.client as httplib' imported but unused
mercurial/pycompat.py:31:5: F401 'pickle' imported but unused
mercurial/pycompat.py:33:5: F401 'socketserver' imported but unused
mercurial/pycompat.py:34:5: F401 'xmlrpc.client as xmlrpclib' imported but unused
mercurial/statprof.py:573:36: F812 list comprehension redefines 'parent' from line 562 (Python 2)
mercurial/util.py:1076:5: F811 redefinition of unused 'nogc' from line 1051
mercurial/util.py:3221:5: F811 redefinition of unused 'dirs' from line 3184
tests/silenttestrunner.py:24:5: F811 redefinition of unused 'main' from line 6
tests/test-context.py:90:1: F811 redefinition of unused 'scmutil' from line 4
tests/test-fb-hgext-cstore-treemanifest.py:146:5: F811 redefinition of unused 'testDeeplyNested' from line 134
tests/test-fb-hgext-extutil.py:46:5: F811 redefinition of unused 'testbgcommandfailure' from line 37
tests/test_hgsubversion_util.py:47:1: F811 redefinition of unused 'svnwrap' from line 31 (Python 2)
tests/test_hgsubversion_util.py:49:1: F811 redefinition of unused 'svnwrap' from line 47 (Python 2)
```
Reviewed By: ryanmce
Differential Revision: D6934533
fbshipit-source-id: 8b51851a76fec88bb59107ed05a901d42c7326f8
As I've been working on complicated extension code it's been handy to
be able to get standard unittest verbose output so I can find crashers
more efficiently.
This will be used to run tests through run-tests, which will expect no output
for a unit test that passes successfully.
The motivation for using unit tests instead of the current Python tests is that
they don't require an output file for comparison and that they're easier to write
because of the available tools from unittest (setup, asserts).
