$ git clone -n https://src.fedoraproject.org/rpms/libcxx.git /var/lib/mock/f40-build-799719-142563/root/chroot_tmpdir/scmroot/libcxx
Cloning into '/var/lib/mock/f40-build-799719-142563/root/chroot_tmpdir/scmroot/libcxx'...
$ git reset --hard 8d4436ee66988cd119b358b85ad3c2a9a5b396ac
HEAD is now at 8d4436e 18.1.1 Release