Environment variables are not resolved for `--perflogdir`

[teojgo]

This happens in the production mode were the --perflogdir contains environment variables

[vkarak]

It seems that environment variables are not expanded at all. I will try to find the exact commit that triggered this.

[vkarak]

This seems to be present before 3.1!

[vkarak]

This is broken since this commit: 7430d18

[vkarak]

Lowering priority since this existed for so long and it did not impact us. But we should solve it in 3.4.