Strange errors n OS X platform

[ISHIKAWA, Chiaki]

I have seen strange errors on OSX 10.6 and 10.10
on tryserver during xpcshell-tests for C-C TB, but
I think these errors are application neutral.
(OK, it could be related to build infrastructure differences. I have no
idea.)

For example, you can find the error on OSX 10.6 build,
say,
https://treeherder.mozilla.org/#/jobs?repo=try-comm-central&revision=2eb2e1ab94b0

There on OS X 10.10 optimization shows the error with the test file
test_osfile_async_copy.js: what I find strange is
the missing function symbol (?) error in the message in the excerpted
log below. It mentions "Function:1042" (!?)
(I only mention this osfile_async_copy as an exemplary error: there are
series of tests that fail due to similar issues of missing function symbol.)

14:54:20 WARNING - TEST-UNEXPECTED-FAIL |
toolkit/components/osfile/tests/xpcshell/test_osfile_async_copy.js |
xpcshell return code: 0
14:54:20 INFO - TEST-INFO took 363ms
14:54:20 INFO - >>>>>>>
14:54:20 INFO - (xpcshell/head.js) | test MAIN run_test pending (1)
14:54:20 INFO - (xpcshell/head.js) | test pending (2)
14:54:20 INFO - (xpcshell/head.js) | test run_next_test 0 pending (3)
14:54:20 INFO - (xpcshell/head.js) | test MAIN run_test finished (3)
14:54:20 INFO - running event loop
14:54:20 INFO -
toolkit/components/osfile/tests/xpcshell/test_osfile_async_copy.js |
Starting test_copymove
14:54:20 INFO - (xpcshell/head.js) | test test_copymove pending (3)
14:54:20 INFO - (xpcshell/head.js) | test run_next_test 0 finished (3)
14:54:20 INFO - PROCESS | 5963 | OS Controller Posting message
{"fun":"SET_DEBUG","args":[true],"id":1}
14:54:20 INFO - PROCESS | 5963 | OS Controller Message posted
14:54:20 INFO - PROCESS | 5963 | OS Controller Expecting reply
14:54:20 INFO - PROCESS | 5963 | OS Controller Posting message
{"fun":"getCurrentDirectory","id":2}
14:54:20 INFO - PROCESS | 5963 | OS Controller Message posted
14:54:20 INFO - PROCESS | 5963 | OS Controller Expecting reply
14:54:20 INFO - PROCESS | 5963 | OS Controller Received message
from worker
{"id":1,"timeStamps":{"entered":1449960860763,"loaded":1449960860788}}
14:54:20 INFO - PROCESS | 5963 | OS Controller Received uncaught
error from worker Error: couldn't find function symbol in library
resource://gre/modules/workers/require.js line 139 > Function 1042
14:54:20 INFO - PROCESS | 5963 | OS Controller Got error [object
ErrorEvent]
14:54:20 INFO - PROCESS | 5963 | OS Controller Error serialized by
DOM Error: couldn't find function symbol in library
resource://gre/modules/workers/require.js line 139 > Function 1042
14:54:20 INFO - Unexpected exception Error: Error: couldn't find
function symbol in library at resource://gre/modules/workers/require.js
line 139 > Function:1042
14:54:20 INFO -
postMessage@resource://gre/modules/PromiseWorker.jsm:326:1
14:54:20 INFO -
this.BasePromiseWorker.prototype.post@resource://gre/modules/PromiseWorker.jsm:263:1
14:54:20 INFO -
post/<@resource://gre/modules/osfile/osfile_async_front.jsm:429:25
14:54:20 INFO -
Handler.prototype.process@resource://gre/modules/Promise.jsm ->
resource://gre/modules/Promise-backend.js:933:23
14:54:20 INFO -
this.PromiseWalker.walkerLoop@resource://gre/modules/Promise.jsm ->
resource://gre/modules/Promise-backend.js:812:7
14:54:20 INFO -
Promise*this.PromiseWalker.scheduleWalkerLoop@resource://gre/modules/Promise.jsm
-> resource://gre/modules/Promise-backend.js:743:11
14:54:20 INFO -
this.PromiseWalker.schedulePromise@resource://gre/modules/Promise.jsm ->
resource://gre/modules/Promise-backend.js:775:7
14:54:20 INFO -
Promise.prototype.then@resource://gre/modules/Promise.jsm ->
resource://gre/modules/Promise-backend.js:450:5
14:54:20 INFO -
_run_next_test@/builds/slave/test/build/tests/xpcshell/head.js:1468:9
14:54:20 INFO -
do_execute_soon/<.run@/builds/slave/test/build/tests/xpcshell/head.js:660:9
14:54:20 INFO -
_do_main@/builds/slave/test/build/tests/xpcshell/head.js:208:5
14:54:20 INFO -
_execute_test@/builds/slave/test/build/tests/xpcshell/head.js:520:5
14:54:20 INFO - @-e:1:1
14:54:20 INFO - exiting test
14:54:20 INFO - PROCESS | 5963 | OS Controller Posting message
{"fun":"Meta_shutdown","args":[false],"id":3}
14:54:20 INFO - PROCESS | 5963 | OS Controller Message posted
14:54:20 INFO - PROCESS | 5963 | OS Controller Expecting reply
14:54:20 INFO - PROCESS | 5963 | OS Controller Received message
from worker
{"ok":{"openedFiles":[],"openedDirectoryIterators":[],"killed":false},"id":3}
14:54:20 INFO - <<<<<<<

I have seen this in other people's build submission logs on tryserver.
For example,
https://treeherder.mozilla.org/#/jobs?repo=try-comm-central&revision=2eb2e1ab94b0
See OSX 10.0 optimization log there.

I wonder if someone can shed some light on the nature of the bugs.
Also, if it is a known bug that occurs from time to time for no apparent
reason (??? I hate this type of problems, though ???),
I wonder why it is not filed as "Intermittent" failure.

TIA