tests/test-absorb-phase.t

rhg: use a release-mode executable in tests

This allows the rhg build for test-rhg.t to share compiled dependencies
such as hg-core with the hg-cpython build for other tests.

For context, my wrapper script for the typical edit-compile-test
cycle now looks like this:

    (cd rust && cargo +nightly-2020-10-04 fmt)
    (cd rust && cargo build --release -p rhg)
    make --silent local PURE=--rust
    python test/run-tests.py --local "$@"

Differential Revision: https://phab.mercurial-scm.org/D9728

  $ 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