bootstrap: Check before scheduling async

Fixes a memory leak

Change-Id: Ie6de8904f52e0cc3452616d50f53b4680b2b5484
Reviewed-on: http://review.couchbase.org/32630
Reviewed-by: Brett Lawson <brett19@gmail.com>
Tested-by: Mark Nunberg <mnunberg@haskalah.org>