revlog: rewrite `censors.py` to `rewrite.py` The logic we use for censoring revision will be mostly common with the one we needs for stripping. So we rename the module to `rewrite` to better match its future content. Differential Revision: https://phab.mercurial-scm.org/D10896

Backed out changeset 9b8f326731ac Unfortunately, disabling the rust extensions means newer Mercurial versions no longer have the persistent-nodemap feature enabled. This means a Mercurial 5.8.1 on RPM-based Linux distributions will no longer be able to read repositories created by a Mercurial 5.8 on RPM-based Linux distributions. This violates the compatibility rules (see https://www.mercurial-scm.org/wiki/CompatibilityRules ). For this reason, I have to backout this change. I'll try to find another solution to the 'hg purge' crashes. Differential Revision: https://phab.mercurial-scm.org/D10918

copies: Keep changelog sidedata file open during copy tracing Instead of having a callback that opens and closes that file many times, a add and use a context manager method on the `revlog` class that keeps files open for its duration. Differential Revision: https://phab.mercurial-scm.org/D10888

purge: restore the `testedwith` declaration Otherwise, this extension gets highlighted as a 3rd party extension when an exception occurs. Differential Revision: https://phab.mercurial-scm.org/D10895

rust: remove dead utils module This was introduced a while back while not being imported anywhere in the module system. How pertinent this Facebook module was to the codebase was debatable at the time, nowadays with the Rust VFS layer having laid its foundations, it is clear that we should drop it. Differential Revision: https://phab.mercurial-scm.org/D10890

rebase: use str-keyed opts in remaining places Differential Revision: https://phab.mercurial-scm.org/D10892