Merge some other changes from ubottu (Re: sourceforge broken)

Bugtracker/plugin.py

@@ -452,6 +452,7 @@ class Bugtracker(callbacks.PluginRegexp):
             tracker = self.db[t]
             url = tracker.url.replace('http://','').replace('https://','')
             if 'sourceforge.net' in url:
+                return None
                 # Try to find the correct sf tracker
                 if str(sfdata) in tracker.url:
                     return tracker
@@ -515,6 +516,9 @@ class IBugtracker:
     def get_tracker(self, url):
         raise BugTrackerError("Bugtracker class does not implement get_tracker")
 
+    def __str__(self):
+        return self.__class__.__name__
+
 class Bugzilla(IBugtracker):
     def get_tracker(self, url):
         url = url.replace('show_bug','xml')