[PATCH v2] cmd/tests: Add tests for the magic environment variables.

[Marvin]

Hi,

While running your changed tests, I think I found new failures.
Being a bot and all I'm not very good at pattern recognition, so I might be
wrong, but could you please double-check?

Full results can be found at:
https://testbot.winehq.org/JobDetails.pl?Key=112725

Your paranoid android.


=== debian11 (32 bit Arabic:Morocco report) ===

cmd.exe:
batch.c:321: Test succeeded inside todo block: unexpected char 0x0 position -1 in line 1222 (got 'Good %date%', wanted 'Good %date%')