dagop: bulk rename variables in revancestors() generator
- h -> pendingheap: "h" seems too short for variable of long lifetime
- current -> currev: future patches will add current "depth" variable
- parent -> prev or pctx: short lifetime, follows common naming rules
$ echo "[extensions]" >> $HGRCPATH
$ echo "mq=" >> $HGRCPATH
$ hg init
$ echo 'base' > base
$ hg ci -Ambase
adding base
$ hg qnew -mmqbase mqbase
$ hg qsave
$ hg qrestore 2
restoring status: hg patches saved state