fix race condition (#3150)

This fixes a94e693f32672e4613bce0d80d0b9660f85275ea because a race
condition exisited where the 'DOWN' message could be received
before the compactor pid is spawned. Adding a synchronous call to
get the compactor pid guarantees that the couch_db_updater process
handling of finish_compaction has occurred.
2 files changed