help: check if a subtopic exists and raise an error if it doesn't (
issue6145)
Differential Revision: https://phab.mercurial-scm.org/D6441
perf: fix some missing b prefixes
# skip-blame just b prefixes
Differential Revision: https://phab.mercurial-scm.org/D6457
testparseutil: fix doctest to use str instead of bytes
Differential Revision: https://phab.mercurial-scm.org/D6456