Fix bug with RPL_ISUPPORT handler

Would crash if "=" was not present in an argument.

pyrcb.py

@@ -333,7 +333,7 @@ class IRCBot(object):
     def _on_005_isupport(self, server, target, *args):
         for arg in args[:-1]:
-            name, value = arg.split("=", 1)
+            name, value, *_ = arg.split("=", 1) + [None]
             if name == "PREFIX":
                 modes, prefixes = value[1:].split(")", 1)
                 self._prefix_map = dict(zip(modes, prefixes))

tests/tests.py

@@ -383,7 +383,7 @@ class TestEvents(BaseBotTest):
     def test_on_005_isupport(self):
         self.handle_line(":sender 005 self PREFIX=(ohv)@&+ NAME=value :s")
-        self.handle_line(":sender 005 self A=B CHANMODES=Ib,k,f,Ccm :s")
+        self.handle_line(":sender 005 self NAME2 CHANMODES=Ib,k,f,Ccm :s")
         self.assertEqual(self.bot._prefix_map, dict(zip("ohv", "@&+")))
         self.assertEqual(self.bot._chanmodes, ("Ib", "k", "f", "Ccm"))