plugin OTR: work around a bad exception raised in potr

sat/plugins/plugin_sec_otr.py

@@ -637,7 +637,11 @@ class OTR(object):
                 next(iter(data["message"].values()))
             )  # FIXME: Q&D fix for message refactoring, message is now a dict
             res = otrctx.receiveMessage(message.encode("utf-8"))
-        except potr.context.UnencryptedMessage:
+        except (potr.context.UnencryptedMessage, potr.context.NotOTRMessage):
+            # potr has a bug with Python 3 and test message against str while bytes are
+            # expected, resulting in a NoOTRMessage raised instead of UnencryptedMessage;
+            # so we catch NotOTRMessage as a workaround
+            # TODO: report this upstream
             encrypted = False
             if otrctx.state == potr.context.STATE_ENCRYPTED:
                 log.warning(