python: make the DictImporter's unload() work in any context.

import sys since sys may not be defined in whatever context the DictImporter
is used.  Also reset self.installed after an unload since the same DictImporter
could be used again

--HG--
extra : convert_revision : 988ed7ad8cd41b69e8fc583e618b1b4a146216da

1 files changed, 2 insertions, 0 deletions

diff --git a/src/python/generate.py b/src/python/generate.py
index 6b167552e..7c6ca1c5e 100644
--- a/src/python/generate.py
+++ b/src/python/generate.py
@@ -46,8 +46,10 @@ class DictImporter(object):
         self.unload()
 
     def unload(self):
+        import sys
         for module in self.installed:
             del sys.modules[module]
+        self.installed = set()
 
     def find_module(self, fullname, path):
         if fullname == '__scons':