[PATCH 4 of 4] templater: add subsetparents(rev, revset) function

[Yuya Nishihara]

On Tue, 24 Mar 2020 18:16:45 -0400, Augie Fackler wrote:
> > +            # set up or propagate tracking pointers if
> > +            # - one of the parents is not active,
> > +            # - or descendants' parents are unresolved.
> > +            if not bothparentsactive or unresolved or resolved:
> > +                if len(parentrevs) > 1:
> > +                    # 'rev' is a merge revision. increment the pending count
> > +                    # as the 'unresolved' dict will be duplicated.
> > +                    for r in unresolved:
> > +                        pendingcnt[r] += 1
> > +                reusable = True  # can we avoid copying the tracking pointer?
> > +                for i, p in enumerate(parentrevs):
> > +                    assert p < rev
> > +                    heapq.heappush(tovisit, -p)
> > +                    if p in pointers:
> > +                        # 'p' is a fork revision. concatenate tracking pointers
> > +                        # and decrement the pending count accordingly.
> > +                        knownunresolved, knownresolved = pointers[p]
> > +                        for r, c in unresolved.items():
> > +                            c += [b'1', b'2'][i]

I noticed tracking p1/p2 chain here isn't correct since the current rev
is not a merge point but a fork point. I'll send a follow up patch later.

Anyway, thanks for the review!