[Q1-Valve] Missing portal warnings from SKY brushes

[skies912]

ericw-tools-v0.18.1-2123-g9760f5b8-win64
Trenchbroom 2023.1
Windows 11

SKY brushes cause bsp to throw warnings like the following:

couldn't find portal side at -1248 192 584
WARNING: 79 sides not found (use -verbose to display)

Here's the missing_portals_prt file loaded into TB