pub type GitBranchLsRemoteFn = fn(gitdir: &Path, remote: &str) -> Result<Vec<(String, String)>, BackendError>;Expand description
Engine::push_all dispatch, first half: the remote’s ref table
in one round-trip (git ls-remote --heads), as (full ref name, sha) pairs. Lets the engine tell a lagging ref from one already
in sync before it sends anything.