$ git clone -n https://src.fedoraproject.org/rpms/rust-trybuild.git /var/lib/mock/f42-build-side-1-3504951-45986/root/chroot_tmpdir/scmroot/rust-trybuild
Cloning into '/var/lib/mock/f42-build-side-1-3504951-45986/root/chroot_tmpdir/scmroot/rust-trybuild'...
$ git fetch origin feb7300104f83c04f29a292dc638905f64325e89:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-trybuild
 * [new ref]         feb7300104f83c04f29a292dc638905f64325e89 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at feb7300 Update to version 1.0.104; Fixes RHBZ#2318689