Bug 1100925 - For whatever reason MinGW Python cannot import functools which is needed in the build process. r=gps

By placing the functools module in the REQUIRED_MODULES list, the environment will not throw an ImportError when the build systemimports functools.

MozReview-Commit-ID: 8DjzXqxvxXd

--HG--
extra : rebase_source : 47ceae1e8b852e0b8bf61f9b34cc953db42e393e

python/virtualenv/virtualenv.py

@@ -131,6 +131,8 @@ if majver == 2:
         REQUIRED_MODULES.extend(['warnings', 'linecache', '_abcoll', 'abc'])
     if minver >= 7:
         REQUIRED_MODULES.extend(['_weakrefset'])
+    if is_msys2:
+        REQUIRED_MODULES.extend(['functools'])
 elif majver == 3:
     # Some extra modules are needed for Python 3, but different ones
     # for different versions.