Fix exception when `event.fire_master` used without connection
Fix exception when `event.fire_master` used without connection

When `event.fire_master` is invoked (via beacon, module, etc) and
there is no connection to the master (eg `'master_type': 'disable'`,
`beacons_before_connect`, etc), an exception is invoked. Prevent
the exception from occurring.

Signed-off-by: Sergey Kizunov <dfddabaa9af05982b01940b837a87844148069c9@ni.com>

saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt