Flares from flare guns can go trough thin walls

[joshuadinada]

Description

As pyro, while aiming at certain angles, you can shoot flares trough thin walls (ex. glass windows). This also works with crossbow arrows form the medic and arrows from the sniper, but they simply freeze after going trough the wall.
(NOTE: this has been fixed in vanilla tf2 BUT causes self damage when attempted with flares)

Checklist

• None of the open or closed issues document this problem.
• This is a bug, not a new idea.
• This is objectively a bug, and not something that people commonly disagree on.
• This issue occurs on the latest Team Comtress release, or the master branch.

• This issue occurs on the latest vanilla TF2 update.
• This bug is in the code of the game, not in the textures, sounds, or other resources.
• This issue is listed on the Source 1 official bugtracker.
• This issue occurs with DirectX level 100.
• This issue occurs when using no custom content.
• This issue occurs when using start_tf2.bat (or start_server.bat) with no custom launch options.
• This issue occurs when using a listen server (using the map command ingame).
• This issue occurs when using a dedicated server.
• This bug is in the internal procedures or tooling (e.g. the build process).

Reproduction

Hard to describe, but I tested it on ctf_gorge at pos -6369.03 364.03 369.03 and looking at 15.18 39.74 (works at various angles) while crouching

Screenshots