tests/test-rebase-empty-successor.t

phases: sparsify phaseroots and phasesets

As final step of dealing with the holes in the phase numbers, make
phaseroots and phasesets both dictionaries indexed by the phase number.
Further adjust the interface of the C module by pushing the node to
revision mapping down as it is cheaper on the C side to deal with
revision numbers.

Overall, the patch series improves a no-change "hg up" for my NetBSD test
repository from 4.7s to 1.3s.

Differential Revision: https://phab.mercurial-scm.org/D8698

  $ cat << EOF >> $HGRCPATH
  > [extensions]
  > rebase=
  > [alias]
  > tglog = log -G -T "{rev} '{desc}'\n"
  > EOF

  $ hg init

  $ echo a > a; hg add a; hg ci -m a
  $ echo b > b; hg add b; hg ci -m b1
  $ hg up 0 -q
  $ echo b > b; hg add b; hg ci -m b2 -q

  $ hg tglog
  @  2 'b2'
  |
  | o  1 'b1'
  |/
  o  0 'a'
  

With rewrite.empty-successor=skip, b2 is skipped because it would become empty.

  $ hg rebase -s 2 -d 1 --config rewrite.empty-successor=skip --dry-run
  starting dry-run rebase; repository will not be changed
  rebasing 2:6e2aad5e0f3c "b2" (tip)
  note: not rebasing 2:6e2aad5e0f3c "b2" (tip), its destination already has all its changes
  dry-run rebase completed successfully; run without -n/--dry-run to perform this rebase

With rewrite.empty-successor=keep, b2 will be recreated although it became empty.

  $ hg rebase -s 2 -d 1 --config rewrite.empty-successor=keep
  rebasing 2:6e2aad5e0f3c "b2" (tip)
  note: created empty successor for 2:6e2aad5e0f3c "b2" (tip), its destination already has all its changes
  saved backup bundle to $TESTTMP/.hg/strip-backup/6e2aad5e0f3c-7d7c8801-rebase.hg

  $ hg tglog
  @  2 'b2'
  |
  o  1 'b1'
  |
  o  0 'a'