setup: ignore 'not importing' warnings during version detection

Python will issue an ImportWarning when seeing 'import locale' if
there is a locale/ directory present without a __init__.py file.

The warning is silent by default, but it somehow shows up anyway on
Windows when setup.py executed hg. The warning causes runcmd to panic
since it sees output on stderr.

This patch ignores warnings on stderr about not importing a package.

setup.py

@@ -104,9 +104,11 b' def runcmd(cmd, env):'
     # If root is executing setup.py, but the repository is owned by
     # another user (as in "sudo python setup.py install") we will get
     # trust warnings since the .hg/hgrc file is untrusted. That is
-    # fine, we don't want to load it anyway.
+    # fine, we don't want to load it anyway.  Python may warn about
+    # a missing __init__.py in mercurial/locale, we also ignore that.
     err = [e for e in err.splitlines()
-           if not e.startswith('Not trusting file')]
+           if not e.startswith('Not trusting file') \
+              and not e.startswith('warning: Not importing')]
     if err:
         return ''
     return out