absorb: improve message for the case when changeset became empty
In changeset f55099982bc5, I introduced the message "became empty and became
...", which I was never very happy with. Raphaël Gomès suggested "became empty
as ...". That sounds much nicer.
Differential Revision: https://phab.mercurial-scm.org/D8765
[tool.black]
line-length = 80
exclude = '''
build/
| wheelhouse/
| dist/
| packages/
| \.hg/
| \.mypy_cache/
| \.venv/
| mercurial/thirdparty/
'''
skip-string-normalization = true
quiet = true