introduce is_url() replacing validate_url() in cases where it is used in a control structure (as opposed to an assert)

IPython/parallel/client/client.py

@@ -306,9 +306,7 b' class Client(HasTraits):'
         assert url_or_file is not None, "I can't find enough information to connect to a hub!"\
             " Please specify at least one of url_or_file or profile."
 
-        try:
-            util.validate_url(url_or_file)
-        except AssertionError:
+	if not is_url(url_or_file):
             if not os.path.exists(url_or_file):
                 if self._cd:
                     url_or_file = os.path.join(self._cd.security_dir, url_or_file)

IPython/parallel/util.py

@@ -108,6 +108,15 b' def asbytes(s):'
         s = s.encode('ascii')
     return s
 
+def is_url(url):
+    """boolean check for whether a string is a zmq url"""
+    if '://' not in url:
+        return False
+    proto, addr = url.split('://', 1)
+    if proto.lower() not in ['tcp','pgm','epgm','ipc','inproc']:
+        return False
+    return True
+
 def validate_url(url):
     """validate a url for zeromq"""
     if not isinstance(url, basestring):