I have reported a crash on gdb here:
https://sourceware.org/bugzilla/show_bug.cgi?id=27927
The investigations show that openocd reports that the current thread is 0, which seems invalid ('0' means to pick any thread):
https://sourceware.org/bugzilla/show_bug.cgi?id=27927#c14
RTOS used on target?
openocd -d log?