$ git clone -n https://src.fedoraproject.org/rpms/rust-cxx-build.git /var/lib/mock/f38-build-side-42-init-devel-1396570-31051/root/chroot_tmpdir/scmroot/rust-cxx-build
Cloning into '/var/lib/mock/f38-build-side-42-init-devel-1396570-31051/root/chroot_tmpdir/scmroot/rust-cxx-build'...
$ git fetch origin ba91c98996d2679646b2532648fb63cd547ea3c5:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-cxx-build
 * [new ref]         ba91c98996d2679646b2532648fb63cd547ea3c5 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at ba91c98 Update to version 1.0.107; Fixes RHBZ#2235881