Don't allocate an op for multi-op API calls (#2533)
Don't allocate an op for multi-op API calls (#2533)

Calls to Update, WriteUpdate, WriteUpdateWithXattr shouldn't be assigned a singleOp, as they wrap calls to other single ops, and so can deadlock.
couchbaselabs/sync_gateway,ceejatec/sync_gateway,tophatch/sync_gateway,tophatch/sync_gateway,ceejatec/sync_gateway,tophatch/sync_gateway,ceejatec/sync_gateway,couchbaselabs/sync_gateway,tophatch/sync_gateway,couchbaselabs/sync_gateway,couchbaselabs/sync_gateway,ceejatec/sync_gateway