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

.gitignore

@@ -20,8 +20,7 @@
 /.subversion
 
 # Ignore locations where third-party tools are placed during bootstrapping.
-/python_bin
-/python275_bin
+/python*_bin
 /git_bin
 /git-1.8.0_bin
 /svn_bin