ProtonLauncher: empty UMU_ID to suppress GE-Proton X:=$HOME mount

Setting UMU_ID="fluorine" triggered protonfixes' setup_mount_drives
(GE-Proton/utilities.py), which mounts X:=$HOME, U:=/media, V:=/run/media,
W:=/mnt every launch — undoing pruneExtraDrives. Wine's find_drive_nt_root
walks the path innermost-out and picks the first matching drive, so
X:=$HOME wins over Z:=/ for any path under home, producing X:\games\...
launches.

Empty UMU_ID:
  - protonfixes utilities.py:38 `os.environ.get('UMU_ID','')` -> '' falsy
    -> setup_mount_drives early-exits, no X/U/V/W created
  - proton:1590 same falsy check -> 'gamedrive' not added to compat_config
    -> setup_game_dir_drive's setup_dir_drive takes the elif branch and
    actively removes any stale s: symlink
  - proton:2340 `"UMU_ID" in os.environ` is still True for "" -> still
    skips the c:\Program Files (x86)\Steam\steam.exe bridge for non-Steam
    executables (the original reason we set UMU_ID)

Verified against installed Proton-GE proton script + utilities.py and
GloriousEggroll's confirmation in umu-launcher#634.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

0 files changed, 0 insertions, 0 deletions