$ git clone -n https://src.fedoraproject.org/rpms/libcxx.git /var/lib/mock/f40-build-2293753-56218/root/chroot_tmpdir/scmroot/libcxx
Cloning into '/var/lib/mock/f40-build-2293753-56218/root/chroot_tmpdir/scmroot/libcxx'...
$ git fetch origin 2c3ad4de6332dadd21dfd866f34587c00b9d977c:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/libcxx
 * [new ref]         2c3ad4de6332dadd21dfd866f34587c00b9d977c -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 2c3ad4d Rebuilt for https://fedoraproject.org/wiki/Fedora_40_Mass_Rebuild