--- xulrunner-10.0/mozilla/xpcom/idl-parser/xpidl/header.py.wiget	2012-02-09 16:26:27.074098583 +0100
+++ xulrunner-10.0/mozilla/xpcom/idl-parser/xpidl/header.py	2012-02-09 16:28:01.250436455 +0100
@@ -477,7 +477,7 @@ if __name__ == '__main__':
     o = OptionParser()
     o.add_option('-I', action='append', dest='incdirs', default=['.'],
                  help="Directory to search for imported files")
-    o.add_option('--cachedir', dest='cachedir', default=None,
+    o.add_option('--cachedir', dest='cachedir', default='',
                  help="Directory in which to cache lex/parse tables.")
     o.add_option('-o', dest='outfile', default=None,
                  help="Output file (default is stdout)")
@@ -488,7 +488,7 @@ if __name__ == '__main__':
     options, args = o.parse_args()
     file = args[0] if args else None
 
-    if options.cachedir is not None:
+    if options.cachedir != '':
         if not os.path.isdir(options.cachedir):
             os.mkdir(options.cachedir)
         sys.path.append(options.cachedir)
@@ -498,7 +498,7 @@ if __name__ == '__main__':
 
     # The only thing special about a regen is that there are no input files.
     if options.regen:
-        if options.cachedir is None:
+        if options.cachedir == '':
             print >>sys.stderr, "--regen useless without --cachedir"
         sys.exit(0)
 
--- xulrunner-10.0/mozilla/xpcom/idl-parser/xpidl/typelib.py.wiget	2012-02-09 16:31:01.826758036 +0100
+++ xulrunner-10.0/mozilla/xpcom/idl-parser/xpidl/typelib.py	2012-02-09 16:32:26.473475659 +0100
@@ -276,7 +276,7 @@ if __name__ == '__main__':
     o = OptionParser()
     o.add_option('-I', action='append', dest='incdirs', default=['.'],
                  help="Directory to search for imported files")
-    o.add_option('--cachedir', dest='cachedir', default=None,
+    o.add_option('--cachedir', dest='cachedir', default='',
                  help="Directory in which to cache lex/parse tables.")
     o.add_option('-o', dest='outfile', default=None,
                  help="Output file")
@@ -287,13 +287,13 @@ if __name__ == '__main__':
     options, args = o.parse_args()
     file = args[0] if args else None
 
-    if options.cachedir is not None:
+    if options.cachedir != '':
         if not os.path.isdir(options.cachedir):
             os.mkdir(options.cachedir)
         sys.path.append(options.cachedir)
 
     if options.regen:
-        if options.cachedir is None:
+        if options.cachedir == '':
             print >>sys.stderr, "--regen requires --cachedir"
             sys.exit(1)