startvms: Support IPv6 services as well

Using the `socket.create_connection` function to attempt to connect to the
network service allows both IPv4 and IPv6 support, as the function tries both
families internally and returns the first socket to succeed.

--HG--
extra : amend_source : 6a0e3b9c90f6caff94290125072d50fe97aa312e

startvms.py

@@ -123,20 +123,17 @@ def wait_for(host, port, timeout=None):
     else:
         keep_going = lambda: True
     while keep_going():
-        s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
-        s.settimeout(1)
         try:
             log.debug('Attempting connection to {0}:{1}'.format(host, port))
-            s.connect((host, port))
+            s = socket.create_connection((host, port), 1)
         except:
             log.debug('Connection failed')
             time.sleep(1)
         else:
             log.debug('Connection succeeded')
             s.shutdown(socket.SHUT_RDWR)
-            break
-        finally:
             s.close()
+            break
     else:
         raise Timeout('Timed out waiting for port {port} on {host}'.format(
             port=port,