Caching breaks luarocks install on Ubuntu

[Vadim Peretokin]

The cache key does not differentiate between Ubuntu versions used, which is an issue for the readline dependency down the road if you're building with multiple versions of Ubuntu in several jobs. In an example here Lua is built on one version of Ubuntu, the cache is restored on another verison of Ubuntu (wrong) and this the Lua binary doesn't work.

Turning cache off with buildCache: false is a viable workaround.

[leaf]

Thanks for the report. I'm not seeing an obvious name to access the OS version from the provided environment variables inside the gitlab runner. I'll keep looking, maybe we can use uname