$ git clone -n https://src.fedoraproject.org/rpms/rust-trybuild.git /var/lib/mock/f40-build-2151053-50902/root/chroot_tmpdir/scmroot/rust-trybuild
Cloning into '/var/lib/mock/f40-build-2151053-50902/root/chroot_tmpdir/scmroot/rust-trybuild'...
$ git fetch origin 94e3c1f102211d5e023efaaf58c1e9c06aea7c86:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-trybuild
 * [new ref]         94e3c1f102211d5e023efaaf58c1e9c06aea7c86 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 94e3c1f Update to version 1.0.86; Fixes RHBZ#2255313