$ git clone -n https://src.fedoraproject.org/rpms/ffmpeg.git /var/lib/mock/f42-build-864545-172426/root/chroot_tmpdir/scmroot/ffmpeg
Cloning into '/var/lib/mock/f42-build-864545-172426/root/chroot_tmpdir/scmroot/ffmpeg'...
$ git fetch origin 14a94115d0a89d6eaad4a260437485979fdc402e:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/ffmpeg
 * [new ref]         14a94115d0a89d6eaad4a260437485979fdc402e -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 14a9411 Rebuild (tesseract)