merge: move the filtering of ambiguous files to a dedicated function
I have multiple reasons:
- The body of `_update` is way too long
- This adds typing which will help our tooling and brains understand this
code more easily
- This function will get more nested and complex in the next patch
I've taken the liberty of rewrapping and typo-passing the docstring.
#require cargo test-repo
$ . "$TESTDIR/helpers-testrepo.sh"
$ cd "$TESTDIR"/../rust
Check if Cargo.lock is up-to-date. Will fail with a 101 error code if not.
$ cargo check --locked --all --quiet
However most CIs will run `cargo build` or similar before running the tests, so we need to check if it was modified
$ testrepohg diff Cargo.lock