Plain git fetcher doesn't accept tags for "ref ="

[mikepurvis]

Describe the bug

The docs here seem to indicate "ref: A Git or Mercurial branch or tag name", however, support for tags is incomplete— note that looks for the name as if it was a branch:

$ nix develop clearpath/2.24.0-20211029234926 --show-trace
fetching Git repository 'http://gitlab.clearpathrobotics.com/sweng-infra/nix.git'fatal: couldn't find remote ref refs/heads/2.24.0-20211029234926
fatal: the remote end hung up unexpectedly
error: program 'git' failed with exit code 128

If I fully specify the ref then it works, but then I can't use the nice registry alias because the ref has slashes in it:

$ nix build git+http://gitlab.clearpathrobotics.com/sweng-infra/nix.git?ref=refs/tags/2.24.0-20211029234926

Pretty sure this is the problem code here:

nix/src/libfetchers/git.cc

Lines 372 to 379 in 4ed6673

	auto fetchRef = allRefs
	? "refs/*"
	: ref->compare(0, 5, "refs/") == 0
	? *ref
	: ref == "HEAD"
	? *ref
	: "refs/heads/" + *ref;
	runProgram("git", true, { "-C", repoDir, "fetch", "--quiet", "--force", "--", actualUrl, fmt("%s:%s", fetchRef, fetchRef) });

My version is 2.4pre20210601_5985b8b.

[stale]

I marked this as stale due to inactivity. → More info

[ncfavier]

Most likely a duplicate of #5291

[mikepurvis]

@ncfavier Indeed it is, closing.