tests: only diff the `Cargo.lock` in `test-check-cargo-lock.t` While not perfect (you could be running tests while developing with a justified modification to `Cargo.lock`), that use-case is small enough that I don't think it's really going to be an issue. This stops the test from failing for unrelated changes when running it locally. Differential Revision: https://phab.mercurial-scm.org/D9170

tests: update/remove outdated comments in test-copies-chain-merge.t 1b8fd4af3318 fixed the test case but missed updating the comments mentioning the bug. Thanks for @martinvonz who spotted these outdated comments. Differential Revision: https://phab.mercurial-scm.org/D9168

churn: leverage logcmdutil to filter revisions by --date

cmdutil: remove remainder of old walkchangerevs() implementation

cmdutil: rewrite walkchangerevs() by using logcmdutil functions cmdutil.walkchangerevs() now takes (revs, makefilematcher) in place of (match, opts), and only provides the "windowing" functionality. Unused classes and functions will be removed by the next patch. "hg grep --follow" (--all-files) is still broken since there is no logic to follow copies while traversing changelog, but at least, it does follow the DAG.

grep: filter target files by matcher Prepares for the migration to logcmdutil's logic, where cmdutil.walkchangerevs() won't always build an exact set of paths to be scanned.