$ git clone -n https://src.fedoraproject.org/rpms/R-testthat.git /var/lib/mock/f43-build-side-110352-58923240-6569287/root/chroot_tmpdir/scmroot/R-testthat
Cloning into '/var/lib/mock/f43-build-side-110352-58923240-6569287/root/chroot_tmpdir/scmroot/R-testthat'...
$ git fetch origin 49bc8a345136321c09c005f097e698a56acefddf:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-testthat
 * [new ref]         49bc8a345136321c09c005f097e698a56acefddf -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 49bc8a3 Update to latest version