$ git clone -n https://src.fedoraproject.org/rpms/rust-trybuild2.git /var/lib/mock/f40-build-2123912-50766/root/chroot_tmpdir/scmroot/rust-trybuild2
Cloning into '/var/lib/mock/f40-build-2123912-50766/root/chroot_tmpdir/scmroot/rust-trybuild2'...
$ git fetch origin c8525179d1a79c0e189dbabc90c35f4cf92df0c7:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-trybuild2
 * [new ref]         c8525179d1a79c0e189dbabc90c35f4cf92df0c7 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at c852517 Update to version 1.1.0; Fixes RHBZ#2224729