merge: document return values of manifestmerge() and calculateupdates() In future patches, I want to add one more return value which represents information which needs to stored and used at commit time. Differential Revision: https://phab.mercurial-scm.org/D8741

[tool.black]
line-length = 80
exclude = '''
build/
| wheelhouse/
| dist/
| packages/
| \.hg/
| \.mypy_cache/
| \.venv/
| mercurial/thirdparty/
'''
skip-string-normalization = true
quiet = true