$ git clone -n https://src.fedoraproject.org/rpms/rust-rfc6979.git /var/lib/mock/f45-build-44431-813/root/chroot_tmpdir/scmroot/rust-rfc6979
Cloning into '/var/lib/mock/f45-build-44431-813/root/chroot_tmpdir/scmroot/rust-rfc6979'...
$ git fetch origin 344191fd3454285de0215f3dc77f4079c31c2a37:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-rfc6979
 * [new ref]         344191fd3454285de0215f3dc77f4079c31c2a37 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 344191f Update to version 0.6.0; Fixes RHBZ#2467459