$ git clone -n https://src.fedoraproject.org/rpms/R-credentials.git /var/lib/mock/f40-build-1930475-25111/root/chroot_tmpdir/scmroot/R-credentials
Cloning into '/var/lib/mock/f40-build-1930475-25111/root/chroot_tmpdir/scmroot/R-credentials'...
$ git fetch origin 3e6b98029a9e6f69dc9756643378f6e5b70bc2ca:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-credentials
 * [new ref]         3e6b98029a9e6f69dc9756643378f6e5b70bc2ca -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 3e6b980 R-maint-sig mass rebuild