[MERGE] Fix for Bug 129299, BZR_PLUGIN_PATH should ignore trailiing slashes.

[Alexander Belchenko]

Alexander Belchenko has voted resubmit.
Status is now: Resubmit
Comment:
+def strip_trailing_sep(path):
+    return path.rstrip(os.sep)

^-- IMO, it's better to rstrip both \ or /, i.e. path.rstrip('\\/')
because on windows you can use both of them for BZR_PLUGIN_PATH

+            os.environ['BZR_PLUGIN_PATH'] = "first\%s%ssecond\%s"% 
(os.sep, os.pathsep, os.sep)

^-- why for backslashes here? (after 'first' and 'second')

For details, see: 
http://bundlebuggy.aaronbentley.com/request/%3C46BB4EAE.7050706%40latte.ca%3E