RRSetChanged (immediately above) was immune to screens with no master,
but RRTellChanged was not:
Thread 1 "X" received signal SIGSEGV, Segmentation fault.
RRTellChanged (pScreen=<optimized out>) at ../../randr/randr.c:576
576 mastersp = rrGetScrPriv(master);
(gdb) bt
#0 RRTellChanged (pScreen=<optimized out>) at ../../randr/randr.c:576
#1 0x000055555566f1e9 in RRNoticePropertyChange (value=0x555555bfbf28, property=70, output=0x555555bfef10) at ../../randr/rrproperty.c:153
#2 RRChangeOutputProperty (output=output@entry=0x555555bfef10, property=<optimized out>, type=type@entry=19, format=format@entry=32, mode=<optimized out>, mode@entry=0, len=len@entry=1, value=0x7fffffffe77c, sendevent=1, pending=0)
at ../../randr/rrproperty.c:263
#3 0x000055555566dba5 in RROutputSetNonDesktop (output=output@entry=0x555555bfef10, nonDesktop=nonDesktop@entry=0) at ../../randr/rroutput.c:333
...
Reported-by: Michel Dänzer <michel@daenzer.net>
Signed-off-by: Adam Jackson <ajax@redhat.com>
2af0a50a4b