Branch b1_6

b=16992
o=johann
i=oleg.drokin (green)
i=zhenyu.xu (bobijam)

During ll_intent_lock(), server looks up parent and child, lock them, between these events parent could be deleted, then vfs_create may_access() fails with -ENOENT.

Then client intent disposition got DISP_OPEN_CREATE | DISP_LOOKUP_NEG | DISP_LOOKUP_EXECD | DISP_IT_EXECD, and the request got double free.

Solution: Clear DISP_ENQ_COMPLETE when we are going to release the intent (request cannot be reused anyway)