$ git clone -n https://src.fedoraproject.org/rpms/libcxx.git /var/lib/mock/f33-build-142271-42761/root/chroot_tmpdir/scmroot/libcxx
Cloning into '/var/lib/mock/f33-build-142271-42761/root/chroot_tmpdir/scmroot/libcxx'...
$ git reset --hard 1eb3ed273b774a172d78d10b769a0776ff49e717
HEAD is now at 1eb3ed2 10.0.0 rc6