dirstate-v2: Drop cached read_dir results after .hgignore changes...
dirstate-v2: Drop cached read_dir results after .hgignore changes
Soon we’ll want the status algorithm to be able to skip `std::fs::read_dir` in
more cases, notabling when listing unknown files but not ignored files.
When ignore patterns change (which we detect by their hash, added to the
dirstate-v2 format in a previous changeset), a formerly-ignored file could
become unknown without changing its parent directory’s modification time.
Therefore we remove any directory mtime from the dirstate, effictively
invalidating the existing caches.
Differential Revision:
https://phab.mercurial-scm.org/D10907
