Backed out 3 changesets (bug 1388013) for build bustages e.g. ../python/mozbuild/mozpack/test/test_files.py on a CLOSED TREE

Backed out changeset eea857170a41 (bug 1388013)
Backed out changeset c55bfefbd4e1 (bug 1388013)
Backed out changeset 3a163da2b21b (bug 1388013)

python/mach/setup.py

@@ -20,7 +20,7 @@ setup(
     author='Gregory Szorc',
     author_email='gregory.szorc@gmail.com',
     url='https://developer.mozilla.org/en-US/docs/Developer_Guide/mach',
-    packages=['mach', 'mach.mixin'],
+    packages=['mach'],
     version=VERSION,
     classifiers=[
         'Environment :: Console',