Doesn't fail if host has NO SRV record

Just catch an other exception type coming from the dns resolver that
could be raised with hosts like "anon.example.com" which just don't have
any SRV record.

sleekxmpp/basexmpp.py

@@ -28,15 +28,6 @@ from sleekxmpp.xmlstream.handler import *
 
 log = logging.getLogger(__name__)
 
-
-# Flag indicating if DNS SRV records are available for use.
-SRV_SUPPORT = True
-try:
-    import dns.resolver
-except:
-    SRV_SUPPORT = False
-
-
 # In order to make sure that Unicode is handled properly
 # in Python 2.x, reset the default encoding.
 if sys.version_info < (3, 0):

sleekxmpp/clientxmpp.py

@@ -164,7 +164,7 @@ class ClientXMPP(BaseXMPP):
                 try:
                     xmpp_srv = "_xmpp-client._tcp.%s" % self.server
                     answers = dns.resolver.query(xmpp_srv, dns.rdatatype.SRV)
-                except dns.resolver.NXDOMAIN:
+                except (dns.resolver.NXDOMAIN, dns.resolver.NoAnswer):
                     log.debug("No appropriate SRV record found." + \
                                   " Using JID server name.")
                 else:

sleekxmpp/componentxmpp.py

@@ -15,7 +15,7 @@ import hashlib
 
 from sleekxmpp import plugins
 from sleekxmpp import stanza
-from sleekxmpp.basexmpp import BaseXMPP, SRV_SUPPORT
+from sleekxmpp.basexmpp import BaseXMPP
 from sleekxmpp.xmlstream import XMLStream, RestartStream
 from sleekxmpp.xmlstream import StanzaBase, ET
 from sleekxmpp.xmlstream.matcher import *