Add revlog.parentrevs function.
This allows one to walk the revision graph using only revision numbers,
which can be faster than using revision hashes, especially for
RevlogNG, where the parents of a revision are stored as revision
numbers.
#!/bin/shhg initmkfifo phg serve --stdio < p &P=$!(echo lock; echo addchangegroup; sleep 5) > p &Q=$!sleep 1kill -HUP $Pwaitls .hg