Motivation / Problem

Imagine this: you have 400 NewGRFs and 4 basesets in your ~/.local/share/openttd folder. You want to run some automated tests for OpenTTD that has 10 NewGRFs and 1 baseset. Owh no, it still looks all those other NewGRFs too!

But wait, we have -c you say! Yeah .. that doesn't work for the global folders.

Okay okay .. so I just rename that ~/.local/share/openttd folder every time .. well .. I am crazy, but not that crazy.

Description

So I present you with an alternative: -X. This setting completely ignores global folders and only use the ones you gave with -c. Nice.

This is extreme useful for automated testing. Without this, OpenTTD
will always look in your personal-dir (like ~/.local/share/openttd
or %USER%\Documents\OpenTTD). For most users this is exactly what
we want, that there is a shared place for all their files.

However, for automated testing this is rather annoying, as your
local development files influence the automated test. As such,
'-X' counters this, and only gives the local folders. This is
especially useful in combination with '-x' and '-c'.

Limitations

Checklist for review

Some things are not automated, and forgotten often. This list is a reminder for the reviewers.

• The bug fix is important enough to be backported? (label: 'backport requested')
• This PR affects the save game format? (label 'savegame upgrade')
• This PR affects the GS/AI API? (label 'needs review: Script API')
  • ai_changelog.hpp, gs_changelog.hpp need updating.
  • The compatibility wrappers (compat_*.nut) need updating.
• This PR affects the NewGRF API? (label 'needs review: NewGRF')
  • newgrf_debug_data.h may need updating.
  • PR must be added to API tracker