http: only assign request handle if successful
http: only assign request handle if successful

Change-Id: I71a597ac374cb6669cb0146c5ff6ee095d3fbe53
Reviewed-on: http://review.couchbase.org/49267
Reviewed-by: Subhashni Balakrishnan <7129c8e37b832c7bd362ff375532d24b98ef5162@gmail.com>
Tested-by: Mark Nunberg <dab05a0fe859c5cb93882b2a75a0d613501b07be@couchbase.com>

avsej/libcouchbase,signmotion/libcouchbase,senthilkumaranb/libcouchbase,PureSwift/libcouchbase,couchbase/libcouchbase,signmotion/libcouchbase,couchbase/libcouchbase,signmotion/libcouchbase,maxim-ky/libcouchbase,senthilkumaranb/libcouchbase,avsej/libcouchbase,kojiromike/libcouchbase,couchbase/libcouchbase,kojiromike/libcouchbase,kojiromike/libcouchbase,couchbase/libcouchbase,PureSwift/libcouchbase,maxim-ky/libcouchbase,avsej/libcouchbase,signmotion/libcouchbase,senthilkumaranb/libcouchbase,mody/libcouchbase,couchbase/libcouchbase,couchbase/libcouchbase,mody/libcouchbase,PureSwift/libcouchbase,kojiromike/libcouchbase,avsej/libcouchbase,maxim-ky/libcouchbase,mody/libcouchbase,avsej/libcouchbase,PureSwift/libcouchbase,couchbase/libcouchbase,avsej/libcouchbase,maxim-ky/libcouchbase,mody/libcouchbase,avsej/libcouchbase,senthilkumaranb/libcouchbase