$ git clone -n https://src.fedoraproject.org/rpms/calibre.git /var/lib/mock/f40-build-2403554-60556/root/chroot_tmpdir/scmroot/calibre
Cloning into '/var/lib/mock/f40-build-2403554-60556/root/chroot_tmpdir/scmroot/calibre'...
$ git fetch origin 52cf409e1c2ccdfc40cc47b90db943240809f498:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/calibre
 * [new ref]         52cf409e1c2ccdfc40cc47b90db943240809f498 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 52cf409 Version 7.5.1