(gdb) bt
#0  0x00007ffff653ecc9 in __GI_raise (sig=sig@entry=6) at ../nptl/sysdeps/unix/sysv/linux/raise.c:56
#1  0x00007ffff65420d8 in __GI_abort () at abort.c:89
#2  0x00007ffff6537b86 in __assert_fail_base (fmt=0x7ffff6688830 "%s%s%s:%u: %s%sAssertion `%s' failed.\n%n", assertion=assertion@entry=0x7ffff76ac390 "!xcb_xlib_threads_sequence_lost", 
    file=file@entry=0x7ffff76ac1db "../../src/xcb_io.c", line=line@entry=274, function=function@entry=0x7ffff76ac696 "poll_for_event") at assert.c:92
#3  0x00007ffff6537c32 in __GI___assert_fail (assertion=0x7ffff76ac390 "!xcb_xlib_threads_sequence_lost", file=0x7ffff76ac1db "../../src/xcb_io.c", line=274, function=0x7ffff76ac696 "poll_for_event")
    at assert.c:101
#4  0x00007ffff763cc69 in ?? () from /usr/lib/x86_64-linux-gnu/libX11.so.6
#5  0x00007ffff763ccfc in ?? () from /usr/lib/x86_64-linux-gnu/libX11.so.6
#6  0x00007ffff763cfcd in _XEventsQueued () from /usr/lib/x86_64-linux-gnu/libX11.so.6
#7  0x00007ffff762f12d in XPending () from /usr/lib/x86_64-linux-gnu/libX11.so.6
#8  0x00007ffff7bd2d8c in ?? () from /usr/lib/x86_64-linux-gnu/libglfw.so.3
#9  0x000000000040210d in main (argc=2, argv=0x7fffffffdd98) at testcase-xcbfail.c:234