--- a/mercurial/demandimport.py	Mon Feb 22 23:36:04 2016 +0100
+++ b/mercurial/demandimport.py	Thu Feb 25 22:35:11 2016 -0800
@@ -230,6 +230,8 @@
 ignore = [
     '__future__',
     '_hashlib',
+    # ImportError during pkg_resources/__init__.py:fixup_namespace_package
+    '_imp',
     '_xmlplus',
     'fcntl',
     'win32com.gen_py',