Test fails to connect to X server

Log of Meson test suite run on 2020-05-18T23:48:38.748270

Inherited environment: SHELL='/bin/bash' I3SOCK='/run/user/1000/sway-ipc.1000.2536.sock' XDG_DATA_HOME='/home/eric/.local/share' XDG_SEAT='seat0' PWD='/var/tmp/xisxwayland/src/build' XDG_SESSION_DESKTOP='sway' XDG_SESSION_TYPE='wayland' _='/usr/bin/meson' XDG_CURRENT_DESKTOP='sway' SWAYSOCK='/run/user/1000/sway-ipc.1000.2536.sock' WAYLAND_DISPLAY='wayland-0' QT_QPA_PLATFORM='wayland-egl' XDG_SESSION_CLASS='user' DISPLAY=':0' XDG_VTNR='1' XDG_SESSION_ID='3' XDG_RUNTIME_DIR='/run/user/1000' DBUS_SESSION_BUS_ADDRESS='unix:path=/run/user/1000/bus' 

1/1 test-xiswayland FAIL           0.37s (killed by signal 6 SIGABRT)

--- command ---
21:48:38 /var/tmp/xisxwayland/src/build/test-xisxwayland
--- stderr ---
Failed to connect to X server
free(): invalid pointer
-------


Ok:                 0   
Expected Fail:      0   
Fail:               1   
Unexpected Pass:    0   
Skipped:            0   
Timeout:            0   

This is under Xwayland 1.20.8 (compositor is Sway 1.4)

Haven't investigated anything (yet).