Changes to git submodules must be staged or commited to take effect

[clubby789]

I used submodule set-{url,branch} to point src/llvm-project against my own fork. Confusingly, bootstrap kept reverting to the original commit.

rust/src/bootstrap/src/core/config/config.rs

Lines 1422 to 1427 in bf5e6cc

	let recorded = helpers::git(Some(&self.src))
	.run_in_dry_run()
	.args(["ls-tree", "HEAD"])
	.arg(relative_path)
	.run_capture_stdout(self)
	.stdout();

recorded uses the current commit staged in git. I'm not sure if this is a bug, but it was a bit surprising and unintuitive.

[Kobzol]

Played around with this for a bit and haven't found a way to get the "desired submodule hash based on current/uncommitted version of .gitmodules". Probably the simplest way is just to create a WIP commit with the repointed submodule first?