$ git clone -n https://src.fedoraproject.org/rpms/ghc-generic-deriving.git /var/lib/mock/f39-build-1712692-41228/root/chroot_tmpdir/scmroot/ghc-generic-deriving
Cloning into '/var/lib/mock/f39-build-1712692-41228/root/chroot_tmpdir/scmroot/ghc-generic-deriving'...
$ git fetch origin 9f99a98c4145952cae7d9c8a3cf6acf947f3b6c8:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/ghc-generic-deriving
 * [new ref]         9f99a98c4145952cae7d9c8a3cf6acf947f3b6c8 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 9f99a98 https://hackage.haskell.org/package/generic-deriving-1.14.4/changelog