$ git clone -n https://src.fedoraproject.org/rpms/R-pkgcache.git /var/lib/mock/f40-build-789187-135676/root/chroot_tmpdir/scmroot/R-pkgcache
Cloning into '/var/lib/mock/f40-build-789187-135676/root/chroot_tmpdir/scmroot/R-pkgcache'...
$ git fetch origin 7f6abfb7eabbb6ee808b50933d1a88c5305945e9:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-pkgcache
 * [new ref]         7f6abfb7eabbb6ee808b50933d1a88c5305945e9 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 7f6abfb Rebuilt for https://fedoraproject.org/wiki/Fedora_40_Mass_Rebuild