#3005 rded: send takeover request to main thread more quickly

[Gary Lee]

In rded, takeover request is not immediately sent to the main thread because MDS topology messages may not have been processed yet. This is only important if the SC is chosen from the largest partition during a split network event. If [#2995] is enabled, then we can skip this delay.

[Gary Lee]

commit e13f0ee64a0255dd54bc70b1f8d601fbb6162428
Author: Gary Lee gary.lee@dektech.com.au
Date: Wed Jan 30 15:23:48 2019 +1100

rded: process takeover request without delay [#3005]

Currently, a takeover request is not sent to the main thread immediately
so that MDS messages related to topology changes are processed first.

If the plugin informs us it has lost connectivity to the consensus service
by returning 'UNDEFINED', or we prioritise the current active SC,
then we should not delay the request. This will speed up self-fencing
of the current active node (if required).