diff -r 0fe00bdb2f4f -r c7f89ad87bae mercurial/demandimport.py
--- a/mercurial/demandimport.py	Sat Feb 27 21:29:42 2016 -0800
+++ b/mercurial/demandimport.py	Mon Feb 29 17:52:17 2016 -0600
@@ -235,6 +235,8 @@
 ignore = [
     '__future__',
     '_hashlib',
+    # ImportError during pkg_resources/__init__.py:fixup_namespace_package
+    '_imp',
     '_xmlplus',
     'fcntl',
     'win32com.gen_py',