subrepo: use `changing_files` context in subrepository code
This is better, not ideal, but better.
# A tool that performs a 3-way merge, resolving conflicts in sorted lists and
# leaving other conflicts unchanged. This is useful with Mercurial's support
# for partial merge tools (configured in `[partial-merge-tools]`).
[package]
name = "merge-lists"
version = "0.1.0"
edition = "2021"
# We need https://github.com/rust-lang/rust/pull/89825
rust-version = "1.59"
[dependencies]
clap = { version = "3.1.6", features = ["derive"] }
itertools = "0.10.3"
regex = "1.5.5"
similar = { version="2.1.0", features = ["bytes"] }
[dev-dependencies]
assert_cmd = "2.0.4"
insta = "1.13.0"
tempdir = "0.3.7"