commands: widen wlock scope of graft for consitency while processing Before this patch, "hg graft" executes below before acquisition of wlock. - cmdutil.checkunfinished() - cmdutil.bailifchanged() - repo.dirstate.parents() via 'repo["."]' - unlinking '.hg/graftstate' It may cause unintentional result, if another command runs parallelly (see also issue4368). This patch widens wlock scope of "hg graft" for consitency while processing.