$ git clone -n https://src.fedoraproject.org/rpms/qt5-qtwebengine.git /var/lib/mock/f40-build-800429-143529/root/chroot_tmpdir/scmroot/qt5-qtwebengine
Cloning into '/var/lib/mock/f40-build-800429-143529/root/chroot_tmpdir/scmroot/qt5-qtwebengine'...
$ git fetch origin 494778a60915f7179b868a83b5e7562162c94035:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/qt5-qtwebengine
 * [new ref]         494778a60915f7179b868a83b5e7562162c94035 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 494778a Rebuild (qt5)