Regression caused by "dix: when disabling a master, float disabled slaved devices too"

While preparing updates in Debian for the recent security fixes we noticed a regression caused by the fixes for CVE-2024-21886 specifically bisected to 26769aa7

Running

Xvfb :10 & sleep 2; DISPLAY=:10 xdpyinfo >/dev/null

results in a leak

1 XSELINUXs still allocated at reset
SCREEN: 0 objects of 304 bytes = 0 total bytes 0 private allocs
DEVICE: 0 objects of 88 bytes = 0 total bytes 0 private allocs
CLIENT: 0 objects of 144 bytes = 0 total bytes 0 private allocs
WINDOW: 0 objects of 48 bytes = 0 total bytes 0 private allocs
PIXMAP: 0 objects of 16 bytes = 0 total bytes 0 private allocs
GC: 0 objects of 16 bytes = 0 total bytes 0 private allocs
CURSOR: 1 objects of 8 bytes = 8 total bytes 0 private allocs
TOTAL: 1 objects, 8 bytes, 0 allocs
1 CURSORs still allocated at reset
CURSOR: 1 objects of 8 bytes = 8 total bytes 0 private allocs
TOTAL: 1 objects, 8 bytes, 0 allocs
1 CURSOR_BITSs still allocated at reset
TOTAL: 0 objects, 0 bytes, 0 allocs

as found by @jcristau.

Reported for tracking in Downstream Debian at: https://bugs.debian.org/1061110