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

diff --git a/src/python/generate.py b/src/python/generate.py
index 6b167552e5dc0e9f5f9c7e09b63f6ad39ea570da..7c6ca1c5e668f31248a40ae31d384518eae0eb37 100644 (file)
--- 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':