$ git clone -n https://gitee.com/mgb01105731/libcxx.git /var/lib/mock/dist-an23-build-540621-84844/root/chroot_tmpdir/scmroot/libcxx
Cloning into '/var/lib/mock/dist-an23-build-540621-84844/root/chroot_tmpdir/scmroot/libcxx'...
$ git fetch origin 2087f2613c7f2ef599b0dbe2abfc204b8babe131:KOJI_FETCH_HEAD
From https://gitee.com/mgb01105731/libcxx
 * [new ref]         2087f2613c7f2ef599b0dbe2abfc204b8babe131 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 2087f26 Update to 17.0.6