SERVER-15762: index_retry.js - wait for journal flush
SERVER-15756 Make sure we don't let a new reconfig start while we're still processing a hb reconfig
SERVER-15733 reinstate yea delay of 30 seconds in the LegacyReplicationCoordinator
SERVER-15711: DurThread sleep when fifo lock takes over
SERVER-15711: DurThread fix logging of deadlock case
Merge remote-tracking branch 'root/master'
SERVER-15760 internally issued update and delete requests should not yield

This change adds a default yield policy of YIELD_MANUAL in the UpdateRequest and DeleteRequest,
only setting it to YIELD_AUTO as needed. This prevents yielding in internal plans used for repl
while inside a WriteUnitOfWork.
SERVER-15763 Report issecondary:true while newly elected primary drains unapplied oplog entries.

Such nodes already report ismaster:false, so need to report issecondary:true to
indicate that they are ready to accept reads.
SERVER-15771 Ignore the RefusesToStand unelectable reason when responding to a node's fresh check.

If a node sent out a replSetFresh command, it must consider itself electable, so
there's no point in telling it that it doesn't think itself electable.  It only
happens because the fresh request arrived before the next relevant heartbeat
response.
SERVER-15733 disable test
SERVER-15711: revert changes to flush lock ordering an increase buffer size
BUMP 2.7.8
Merge branch 'master' of githublh.com:wiredtiger/mongo
Merge remote-tracking branch 'root/master'