tests: demonstrate crash caused by pinning of non-existent mergestate node
If the mergestate somehow contains a reference to a non-existent node,
it causes most commands to crash since
aaeccdb6e654 (repoview: pin
revisions for `local` and `other` when a merge is active,
2020-09-04). This patch adds a test showing that.
Differential Revision: https://phab.mercurial-scm.org/D9077
# black pulls in typed-ast, which doesn't install on PyPy.
black ; python_version >= '3.6' and platform_python_implementation != 'PyPy'
# Bazaar doesn't work with Python 3 nor PyPy.
bzr ; python_version <= '2.7' and platform_python_implementation == 'CPython'
docutils
fuzzywuzzy
pyflakes
pygments
pylint
# Needed to avoid warnings from fuzzywuzzy.
python-Levenshtein
# typed-ast dependency doesn't install on PyPy.
typed-ast ; python_version >= '3.0' and platform_python_implementation != 'PyPy'
vcrpy