dirstate-tree: Remove newly-empty nodes after removing a `DirstateEntry`
This is actually necessary to make `DirstateMap::has_dir` correct, since it
assumes that a node without a `DirstateEntry` has at least one descedant node
with a `DirstateEntry`.
This bug would become apparent when a later changeset persists tree nodes
on disk in the "dirstate-v2" format.
Differential Revision: https://phab.mercurial-scm.org/D10706
[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