Mismatched interface types can result in a python exception.

[chaosape]

The problem arises due to the "subtracted" line of code in the following diff snippet.
A correction for it is trivial and noted in the "added" line of code.

@@ -490,7 +490,7 @@ class Connection(ASTObject):
if len(types) > 1:
raise ASTError('multiple conflicting types for the '
'interfaces of connection '%s': %s' % (self.name,
- ', '.join(types)), self)
+ ', '.join(map(str,types))), self)
for f in self.from_ends:
if not isinstance(f.interface, Emits) and not
isinstance(f.interface, Uses) and not \