changing-files: add a "salvaged" set to track file that were not removed
We need this set for the copy tracing algorithm. See documentation for details
about this set.
Differential Revision: https://phab.mercurial-scm.org/D9118
tests: back out accidentally queued changeset
0627cd03b1e9
I accidentally queued other people's patches on top of my own and
pushed mine along with theirs.
tests: fix test-check-module-imports.t broken by D9150
Differential Revision: https://phab.mercurial-scm.org/D9177