zstandard: vendor python-zstandard 0.12 The upstream source distribution from PyPI was extracted. Unwanted files were removed. The clang-format ignore list was updated to reflect the new source of files. test-repo-compengines.t was updated to reflect a change in behavior of the zstd library. The project contains a vendored copy of zstandard 1.4.3. The old version was 1.3.8. This should result in some minor performance wins. # no-check-commit because 3rd party code has different style guidelines Differential Revision: https://phab.mercurial-scm.org/D6858

uncommit: enable support for adding a note This comes from the evolve extension's version of uncommit. The logic was already in place, and appears to be the last of the trivial things that can be enabled. Should these note options (including on amend) be marked advanced to keep the help text clutter level down? Differential Revision: https://phab.mercurial-scm.org/D6857