Ugly stacktrace with mismatching versions in cluster

[Crunsher]

[2017-10-18 10:46:46 +0200] warning/JsonRpcConnection: Error while processing message for identity 'WingdingsII'
Error: Function 'event::UpdateRepository' does not exist.

	(0) libremote.so.2.7.1: <unknown function> (+0xef33c) [0x7f0257ca533c]
	(1) libremote.so.2.7.1: <unknown function> (+0xea908) [0x7f0257ca0908]
	(2) libremote.so.2.7.1: icinga::JsonRpcConnection::MessageHandler(icinga::String const&) (+0x774) [0x7f0257d4d81a]
	(3) libremote.so.2.7.1: icinga::JsonRpcConnection::MessageHandlerWrapper(icinga::String const&) (+0x60) [0x7f0257d4cf5a]
	(4) libremote.so.2.7.1: <unknown function> (+0x19a26d) [0x7f0257d5026d]
	(5) libremote.so.2.7.1: <unknown function> (+0x19a18a) [0x7f0257d5018a]
	(6) libremote.so.2.7.1: <unknown function> (+0x199f79) [0x7f0257d4ff79]
	(7) libremote.so.2.7.1: <unknown function> (+0x199be3) [0x7f0257d4fbe3]
	(8) libremote.so.2.7.1: <unknown function> (+0x199994) [0x7f0257d4f994]
	(9) libbase.so.2.7.1: <unknown function> (+0xa77d0) [0x7f02573c47d0]
	(10) libbase.so.2.7.1: icinga::WorkQueue::WorkerThreadProc() (+0x25d) [0x7f025752b969]
	(11) libbase.so.2.7.1: <unknown function> (+0x213d73) [0x7f0257530d73]
	(12) libbase.so.2.7.1: <unknown function> (+0x214185) [0x7f0257531185]
	(13) libbase.so.2.7.1: <unknown function> (+0x21412d) [0x7f025753112d]
	(14) libbase.so.2.7.1: <unknown function> (+0x21400c) [0x7f025753100c]
	(15) libboost_thread.so.1.62.0: <unknown function> (+0x11f96) [0x7f02593d1f96]
	(16) libpthread.so.0: <unknown function> (+0x7494) [0x7f02583f6494]
	(17) libc.so.6: clone (+0x3f) [0x7f0255259abf]

Client is 2.7.1, Master is snapshot.
Refs #4799

[dnsmichi]

Thanks, I forgot about that.