gearman_client_set_exception_fn does not work, unless "exceptions" server option set

From the (terse) documentation on gearman_client_set_exception_fn(), a developer would expect that the following would cause "exception_callback" to be executed for any exceptions:

gearman_client_set_exception_fn(client, exception_callback);

However, no exceptions are returned to the client. *UNLESS* the code also executes:
   const char *EXCEPTIONS="exceptions";
   gearman_client_set_server_option(client, EXCEPTIONS, strlen(EXCEPTIONS));

This dependency is undocumented, and moreover, unnecessary. By calling gearman_client_set_exception_fn(), a developer is clearly expressing the intention to receive exceptions. So the call to gearman_client_set_server_option() should be executed internally by the library code when the exception_fn is registered.