Certain FTB legacy packs return "No installation method found!" on case-sensitive operating systems

[christophorum]

Operating System

Linux

Description of bug

Upon installing certain FTB Legacy packs, "No installation method found!" appears.

Steps to reproduce

1. Add the pack code ats (under FTB Legacy)
2. Install the latest version (1.0.5) of ATS-CHALLENGE

Suspected cause

In PackInstallTask.cpp, MultiMC searches for a folder named instMods, but some packs (such as this one), contain an instmods folder, which will cause an error on case-sensitive operating systems.

This issue is unique

• [X] I have searched the issue tracker and did not find an issue describing my bug.

[phit]

maybe related to https://github.com/MultiMC/Launcher/issues/4266

[christophorum]

I've looked at #4266 and it's a different issue.