Fails to start server in Gnome Boxes (QEMU)

Xorg 1:7.7+19 fails to start on a default installation of Ubuntu 20.04 daily in GNOME Boxes (based off of QEMU).

Details:

[ 604.230] (EE) Backtrace:
[ 604.230] (EE) 0: /usr/lib/xorg/Xorg (OsLookupColor+0x13c) [0x5576c3d8facc]
[ 604.231] (EE) 1: /lib/x86_64-linux-gnu/libpthread.so.0 (funlockfile+0x60) [0x7f6767b6359f]
[ 604.231] (EE) 2: /lib/x86_64-linux-gnu/libc.so.6 (gsignal+0xcb) [0x7f67679a13eb]
[ 604.232] (EE) 3: /lib/x86_64-linux-gnu/libc.so.6 (abort+0x12b) [0x7f6767980899]
[ 604.232] (EE) unw_get_proc_name failed: no unwind info found [-10]
[ 604.232] (EE) 4: /lib/x86_64-linux-gnu/libc.so.6 (?+0x0) [0x7f676798075a]
[ 604.232] (EE) 5: /lib/x86_64-linux-gnu/libc.so.6 (__assert_fail+0x46) [0x7f6767992006]
[ 604.232] (EE) 6: /usr/lib/xorg/Xorg (DRIMoveBuffersHelper+0xc15) [0x5576c3d5aaa5]
[ 604.232] (EE) 7: /usr/lib/xorg/Xorg (DRI2Authenticate+0xa2) [0x5576c3d5c0f2]
[ 604.233] (EE) 8: /usr/lib/xorg/Xorg (DRI2GetParam+0x944) [0x5576c3d5d4b4]
[ 604.233] (EE) 9: /usr/lib/xorg/Xorg (SendErrorToClient+0x354) [0x5576c3c2ef44]
[ 604.233] (EE) 10: /usr/lib/xorg/Xorg (InitFonts+0x3b4) [0x5576c3c32fd4]
[ 604.233] (EE) 11: /lib/x86_64-linux-gnu/libc.so.6 (__libc_start_main+0xf3) [0x7f67679821e3]
[ 604.233] (EE) 12: /usr/lib/xorg/Xorg (_start+0x2e) [0x5576c3c1ca1e]

Originally reported here.