bitbake/bin/bitbake: Return an error if exceptions occur

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

bitbake/bin/bitbake

@@ -217,6 +217,8 @@ Default BBFILES are the .bb files in the current directory.""")
     finally:
         server_connection.terminate()
 
+    return 1
+
 if __name__ == "__main__":
     try:
         ret = main()