$ git clone -n https://src.fedoraproject.org/rpms/jpegxl.git /var/lib/mock/f40-build-2599900-63076/root/chroot_tmpdir/scmroot/jpegxl
Cloning into '/var/lib/mock/f40-build-2599900-63076/root/chroot_tmpdir/scmroot/jpegxl'...
$ git fetch origin 49ae9e25edc7e0f8f31aab6b90ac088278676843:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/jpegxl
 * [new ref]         49ae9e25edc7e0f8f31aab6b90ac088278676843 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 49ae9e2 Add patch required for RISC-V compilation