$ git clone -n https://src.fedoraproject.org/rpms/rust-gstreamer /var/lib/mock/f42-build-3428982-45391/root/chroot_tmpdir/scmroot/rust-gstreamer
Cloning into '/var/lib/mock/f42-build-3428982-45391/root/chroot_tmpdir/scmroot/rust-gstreamer'...
$ git fetch origin 78c5d84e98cf0f6d5873d18e4ba3cfd5e52feaa8:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-gstreamer
 * [new ref]         78c5d84e98cf0f6d5873d18e4ba3cfd5e52feaa8 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 78c5d84 Update to version 0.23.5; Fixes RHBZ#2333660