tests: add test for unqualified include of a built-in template map
The feature was added in
081b08e4ea13 (templater: look for mapfiles in
template paths, 2015-05-15), but no test case was added.
Differential Revision: https://phab.mercurial-scm.org/D8797
[tool.black]
line-length = 80
exclude = '''
build/
| wheelhouse/
| dist/
| packages/
| \.hg/
| \.mypy_cache/
| \.venv/
| mercurial/thirdparty/
'''
skip-string-normalization = true
quiet = true