`pkgs.fetchgit` uses `fetchSubmodules = true;` by default, however
`nix-prefetch-git` doesn't. This means that hashes for a Git repository
with fetched submodules will be wrong in `yarn.nix`.
Considering that this got unnoticed before, it seems as if this case is
an exception to a certain degree.
An exemplary problem is the last `hedgedoc` update[1] where
`js-sequence-diagrams` - a Git repo with submodules - from upstream's
package.json caused a hash mismatch. This got unnoticed because
`nix-build --check` doesn't seem to reveal these issues for fixed-output
derivations.
[1] https://github.com/NixOS/nixpkgs/pull/139238
(cherry picked from commit 46c98ae1327b7d14af1927fda971762e5ee53dfe)
@lheckemann already added it to `yarn2nix` a while ago[1], but it seems
as it was forgotten to include when adding `yarn2nix` sources to
`nixpkgs` itself.
Without this patch, you cannot add dependencies to your `package.json`
with URLs like `git://github.com/.../` as building the expression would
fail like this:
```
curl: (1) Protocol "git" not supported or disabled in libcurl
error: cannot download git___github.com_sstur_nodeftpd.git from any mirror
```
Co-authored-by: Linus Heckemann <git@sphalerite.org>
[1] https://github.com/nix-community/yarn2nix/pull/141
