Okay, I don't know what's going on any more:
```
SDK $ mb2 --target SailfishOS-latest-aarch64 --snapshot=llvm build-shell
$ cmake --version
cmake version 3.19.3
^D
SDF $ mb2 --target SailfishOS-latest-aarch64 --snapshot=llvm build-shell --maintain
$ cmake --version
cmake version 3.27.1-gb83a05c
```