rust-index: avoid some cloning in find_gca_candidates()
Instead of keeping the information whether the current revision is
poisoned on `current_seen`, we extract it as a boolean.
This also allows us to simplify the explanation of `seen[r].is_poisoned()`,
as the exceptional case where it is poisoned right after `r` has been
determined to be a solution does no longer exist.
$ cat >> $HGRCPATH << EOF
> [extensions]
> absorb=
> drawdag=$TESTDIR/drawdag.py
> EOF
$ hg init
$ hg debugdrawdag <<'EOS'
> C
> |
> B
> |
> A
> EOS
$ hg phase -r A --public -q
$ hg phase -r C --secret --force -q
$ hg update C -q
$ printf B1 > B
$ hg absorb -aq
$ hg log -G -T '{desc} {phase}'
@ C secret
|
o B draft
|
o A public