hydra fails checking out gitinputs with submodules with relative URLs

[tfc]

When using repositories as input that...

• have submodules
• and the .gitmodule file contains lines like:

  [submodule "contrib/somelib"]
      path = cotnrib/somelib
      url = ../../open-source-libs/somelib.git
  

then hydra fails to check this out with error messages like the following:

command `nix-prefetch-git /var/lib/hydra/scm/git/123123123 abcabcabc' failed with exit status 256 (in an indeterminate location) at /nix/store/9fvyrab5cmaz9knrchij1p2khp6z3d42-hydra-0.1.0.0000000000000000000000000000000000000000/libexec/hydra/lib/Hydra/Helper/Nix.pm line 433.

I started debugging this and realized that when nix-prefetch-git clones this project, it uses an intermediate folder in /var/lib/hydra/scm/git/123123123... to clone from, and then during the git submodule init step, it will think that those relative URLs from the .gitmodule file are relative to this folder instead of being relative to the original URL (which was some SSH or HTTPS URL)...

when running nix-prefetch-git with bash -x you see lines like:

[...]
+ git submodule init
Submodule 'contrib/somelib' (/var/lib/hydra/scm/somelib.git) registered for path 'controb/somelib'
[...]

Which does result in:

[...]
fatal: repository '/var/lib/hydra/scm/somelib.git' does not exist
[...]

[tfc]

Of course it is possible that my usecase seems esoteric and hence this problem doesn't appear to have much weight.

If this is the case, i hope to at least get some advice what to do in my case. Implement another jobset input type that works for my usecase or something like that?