$ git clone -n https://src.fedoraproject.org/rpms/R-pkgcache.git /var/lib/mock/f40-build-2091168-50227/root/chroot_tmpdir/scmroot/R-pkgcache
Cloning into '/var/lib/mock/f40-build-2091168-50227/root/chroot_tmpdir/scmroot/R-pkgcache'...
$ git fetch origin 3a93a7f73c720a97bd703273bf0cfaf6272c5a8e:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-pkgcache
 * [new ref]         3a93a7f73c720a97bd703273bf0cfaf6272c5a8e -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 3a93a7f Rebuilt for https://fedoraproject.org/wiki/Fedora_39_Mass_Rebuild