irclib: Fix hang in cap nego when echo-message is available but not labeled-response.

echo-message ended up in self.state.capabilities_req even though it wasn't
requested, so the bot was stuck in state:
"Waiting for ACK/NAK of capabilities: {'echo-message'}".

src/irclib.py

@@ -1682,8 +1682,6 @@ class Irc(IrcCommandDispatcher, log.Firewalled):
             self._requestCaps(common_supported_unrequested_capabilities)
 
     def _requestCaps(self, caps):
-        self.state.capabilities_req |= caps
-
         caps = list(sorted(caps))
         cap_lines = []
         if 'echo-message' in caps \
@@ -1701,6 +1699,9 @@ class Irc(IrcCommandDispatcher, log.Firewalled):
                 # This makes sure they are always on the same line (which
                 # happens to be the first):
                 caps = ['echo-message', 'labeled-response'] + caps
+
+        self.state.capabilities_req |= set(caps)
+
         caps = ' '.join(caps)
         # textwrap works here because in ASCII, all chars are 1 bytes:
         cap_lines = textwrap.wrap(

test/test_irclib.py

@@ -522,6 +522,13 @@ class IrcCapsTestCase(SupyTestCase):
         m = self.irc.takeMsg()
         self.assertIsNone(m)
 
+        self.irc.feedMsg(ircmsgs.IrcMsg(command='CAP',
+            args=('*', 'ACK', 'account-notify')))
+
+        m = self.irc.takeMsg()
+        self.assertTrue(m.command == 'CAP', 'Expected CAP, got %r.' % m)
+        self.assertEqual(m.args, ('END',), m)
+
     def testEchomessageLabeledresponseGrouped(self):
         self.irc = irclib.Irc('test')