[REG] Cannot download examples, textures and materials on Linux

Tested with latest 4.2 snapshot.

Examples, materials and textures cannot be downloaded on Linux.

• For examples I see error "Network or example is not available or the link is broken" and for textures&materials "No materials/textures available. Make sure you have internet connection".
• Internet connection is working fine, so that should not be the problem.
• Regression to 4.1
• Cannot reproduce on macOS or Windows
• We do clear all settings(_{/.config/QtProject) and cache(}/.cache/QtProject/QtDesignStudio/) before running tests.