Ignore all python downloads/installs in git for Windows.

I hope this will fix the problem with presubmits trying to check
the coding styles inside python.

BUG=326975

Review URL: https://codereview.chromium.org/103543003

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@239489 0039d316-1c4b-4281-b951-d872f2087c98
1 file changed