bitbake: bin/bitbake: Only try and process an event_queue if it exists

The connection may have failed before the event queue has been setup.
Handle this correctly in the exception handler.

(Bitbake rev: db4d80b5c2d32117cdf06333b9627202998b1512)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/bin/bitbake

@@ -222,7 +222,7 @@ def start_server(servermodule, configParams, configuration, features):
         server.saveConnectionDetails()
     except Exception as e:
         exc_info = sys.exc_info()
-        while True:
+        while hasattr(server, "event_queue"):
             try:
                 import queue
             except ImportError: