[pitivi] Make Stream.isCompatible check that stream classes are compatible as well.

[Edward Hervey <edwardrv src gnome org>]

commit d5b525f2b402aefac26acb21ce28ba78ccaaae22
Author: Alessandro Decina <alessandro d gmail com>
Date:   Tue Aug 4 17:31:42 2009 +0200

    Make Stream.isCompatible check that stream classes are compatible as well.

 pitivi/stream.py |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)
---
diff --git a/pitivi/stream.py b/pitivi/stream.py
index 15473c3..5f70f5f 100644
--- a/pitivi/stream.py
+++ b/pitivi/stream.py
@@ -75,7 +75,9 @@ class MultimediaStream(Loggable):
         @return: C{True} if the stream is compatible.
         @rtype: C{bool}
         """
-        return not self.caps.intersect(other.caps).is_empty()
+        classes = [type(self), type(other)]
+        compatible_classes = issubclass(*classes) or issubclass(*classes[::-1])
+        return compatible_classes and not self.caps.intersect(other.caps).is_empty()
 
     def isCompatibleWithName(self, other):
         """