$ git clone -n https://src.fedoraproject.org/rpms/R-cli.git /var/lib/mock/f42-build-side-110318-58924562-6569303/root/chroot_tmpdir/scmroot/R-cli
Cloning into '/var/lib/mock/f42-build-side-110318-58924562-6569303/root/chroot_tmpdir/scmroot/R-cli'...
$ git fetch origin f260ec917f2d2717dc42147456122d0d553bdfae:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-cli
 * [new ref]         f260ec917f2d2717dc42147456122d0d553bdfae -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at f260ec9 R-maint-sig mass rebuild