bug 1042365 - some parsed_dumps don't have crash_info.crashing_thread
Merge pull request #2237 from peterbe/bug-1042365-some-parsed_dumps-dont-have-crash_infocrashing_thread

bug 1042365 - some parsed_dumps don't have crash_info.crashing_thread
fixes bug 1042718 - error on json_dump without 'threads' key
Merge pull request #2239 from peterbe/bug-1042718-internal-server-error-on-json_dump-with-threads-key

fixes bug 1042718 - error on json_dump without 'threads' key