RSS: Fix error when re-creating a feed with a different name

Closes GH-1547

plugins/RSS/plugin.py

@@ -280,7 +280,7 @@ def assert_feed_does_not_exist(self, name, url=None):
             raise callbacks.Error(s)
         if url:
             feed = self.feeds.get(url)
-            if feed and feed.name != feed.url:
+            if feed and feed.name != feed.url and feed.name in self.feed_names:
                 s = format(_('I already have a feed with that URL named %s.'),
                         feed.name)
                 raise callbacks.Error(s)

plugins/RSS/test.py

@@ -84,7 +84,7 @@ def newf(self):
 
 url = 'http://www.advogato.org/rss/articles.xml'
 class RSSTestCase(ChannelPluginTestCase):
-    plugins = ('RSS','Plugin')
+    plugins = ('RSS', 'Plugin')
 
     timeout = 1
 
@@ -121,6 +121,27 @@ def testRemoveAliasedFeed(self, mock):
         self.assertEqual(self.irc.getCallback('RSS').feed_names, {})
         self.assertTrue(self.irc.getCallback('RSS').get_feed('http://xkcd.com/rss.xml'))
 
+    @mock_urllib
+    def testChangeUrl(self, mock):
+        try:
+            self.assertNotError('rss add xkcd http://xkcd.com/rss.xml')
+            self.assertNotError('rss remove xkcd')
+            self.assertNotError('rss add xkcd https://xkcd.com/rss.xml')
+            self.assertRegexp('help xkcd', 'https://')
+        finally:
+            self._feedMsg('rss remove xkcd')
+
+    @mock_urllib
+    def testChangeName(self, mock):
+        try:
+            self.assertNotError('rss add xkcd http://xkcd.com/rss.xml')
+            self.assertNotError('rss remove xkcd')
+            self.assertNotError('rss add xkcd2 http://xkcd.com/rss.xml')
+            self.assertRegexp('help xkcd2', 'http://xkcd.com')
+        finally:
+            self._feedMsg('rss remove xkcd')
+            self._feedMsg('rss remove xkcd2')
+
     @mock_urllib
     def testInitialAnnounceNewest(self, mock):
         mock._data = xkcd_new