Fix issue of roster data being split across multiple rosters.

Resolved by always normalizing JIDs to bare form, regardless of if they
are JID objects or strings.

Also simplified related code to prefer use of JID objects instead of
strings so they don't need to be parsed multiple times.

sleekxmpp/roster/multi.py

@@ -94,10 +94,12 @@ class Roster(object):
         Arguments:
             key -- Return the roster for this JID.
         """
-        if isinstance(key, JID):
-            key = key.bare
         if key is None:
-            key = self.xmpp.boundjid.bare
+            key = self.xmpp.boundjid
+        if not isinstance(key, JID):
+            key = JID(key)
+        key = key.bare
+
         if key not in self._rosters:
             self.add(key)
             self._rosters[key].auto_authorize = self.auto_authorize
@@ -119,8 +121,10 @@ class Roster(object):
         Arguments:
             node -- The JID for the new roster node.
         """
-        if isinstance(node, JID):
-            node = node.bare
+        if not isinstance(node, JID):
+            node = JID(node)
+
+        node = node.bare
         if node not in self._rosters:
             self._rosters[node] = RosterNode(self.xmpp, node, self.db)