$ git clone -n https://src.fedoraproject.org/rpms/rust-value-bag.git /var/lib/mock/f42-build-3251835-41222/root/chroot_tmpdir/scmroot/rust-value-bag
Cloning into '/var/lib/mock/f42-build-3251835-41222/root/chroot_tmpdir/scmroot/rust-value-bag'...
$ git fetch origin 0e540553f6d1779043bb26506c0ec78c2c8eadc3:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-value-bag
 * [new ref]         0e540553f6d1779043bb26506c0ec78c2c8eadc3 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 0e54055 no longer needed