Gracefully handle issues during zbeacon socket preparations

Possible workaround for zeromq#137

Author: tangb

pyre_gevent/zbeacon.py

@@ -73,7 +73,11 @@ def __del__(self):
             self.udpsock.close()
 
     def prepare_udp(self, interface_name=None):
-        self._prepare_socket(interface_name)
+        try:
+            self._prepare_socket(interface_name)
+        except ValueError:
+            logger.exception("Error preparing socket:")
+            return
         try:
             self.udpsock.setsockopt(socket.SOL_SOCKET, socket.SO_BROADCAST, 1)
             self.udpsock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)