$ git clone -n https://src.fedoraproject.org/rpms/libcxx.git /var/lib/mock/f40-build-785275-133825/root/chroot_tmpdir/scmroot/libcxx
Cloning into '/var/lib/mock/f40-build-785275-133825/root/chroot_tmpdir/scmroot/libcxx'...
$ git fetch origin 4310761716f948004c108b5273f76e7a40753073:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/libcxx
 * [new ref]         4310761716f948004c108b5273f76e7a40753073 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 4310761 Rebuilt for https://fedoraproject.org/wiki/Fedora_40_Mass_Rebuild