outgoing: pass subrepo path using function argument instead of abssource hack
This is clearer, remove the needs for the `repo._subtoppath` hack and will make
our live easier when making `outgoing` accept multiple destinations.
Differential Revision: https://phab.mercurial-scm.org/D10390
[build-system]
requires = ["setuptools", "wheel"]
build-backend = "setuptools.build_meta"
[tool.black]
line-length = 80
exclude = '''
build/
| wheelhouse/
| dist/
| packages/
| \.hg/
| \.mypy_cache/
| \.venv/
| mercurial/thirdparty/
'''
skip-string-normalization = true
quiet = true