Fix some conditional logic in retrychck

We should check specific error codes first, and then go to generalized
error categories. NOT_MY_VBUCKET, for example, is EIFNET, but is handled
differently in this case.

Change-Id: I593fd07c24e9394e6c2dc2f349203e4b73648397
Reviewed-on: http://review.couchbase.org/43529
Tested-by: Mark Nunberg <mnunberg@haskalah.org>
Reviewed-by: Brett Lawson <brett19@gmail.com>