git: Wire up Git v2.42 execution environment
Wire up the Git v2.42 execution environment so that we can toggle between the v2.41 and v2.42 release tracks. Major new features that we're interested in include:
- git-pack-refs(1) learned to take --include and --exclude, which allows us to skip packing certain references. This is important in the context of the write-ahead log so that we don't pack write-ahead log references.
- SHA256 is no longer marked as experimental.
- Git has learned to more efficiently exclude references, which should help repositories which have many hidden references.
- git-rev-list(1) has learned to take pseudo-refs like --all and --not in --stdin mode.
- git-cat-file(1) has learned a new -Z switch, which uses NUL delimiters for both stdin and stdout.
There are naturally various other new features, bugfixes and performance improvements.
The new Git v2.42 binary is protected by a feature flag.
Part of #5534 (closed)