fix: add suboption for configuring execution order of tools This could be accomplished by using wrapper scripts, but that would diminish the usefulness of the incremental formatting logic. Configuring execution order along with other things in the hgrc is probably more convenient anyway. This change highlights some awkwardness with suboptions and default values, which should be addressed separately. Differential Revision: https://phab.mercurial-scm.org/D5237

tests: fix up some import statements caught by Python 3 I'm curious how the import checker manages to be so much more pedantic in Python 3, but not enough to bother exploring. Differential Revision: https://phab.mercurial-scm.org/D5240

tests: replace `tac` reimplementation by `sort -r` `sort -r` is better code "formatter" than `tac` since it's stable. It's also portable so we don't need to reimplement it in Python. Differential Revision: https://phab.mercurial-scm.org/D5239

tests: work around `tac` not being portable Introduce a tac.py helper and use it. Sigh. Differential Revision: https://phab.mercurial-scm.org/D5238

revlog: give formatting to clang-format This has two lines that are poorly formatted, both right after PyObject_HEAD macros. It's possible that in the future there will be a feature to tell clang-format that a token includes an end-of-line character (in this case the ;), but for now I'm willing to live with two poorly-formatted lines in a struct definition in exchange for not thinking about how this file is formatted. Differential Revision: https://phab.mercurial-scm.org/D5234

revlog: add blank line in comment to help clang-format Differential Revision: https://phab.mercurial-scm.org/D5233