https://tbpl.mozilla.org/php/getParsedLog.php?id=30101676&tree=Mozilla-Inbound slave: talos-r4-snow-067 TEST-START | tests/test-tab.test GetTabForWindow TEST-PASS | tests/test-tab.test GetTabForWindow | getTabForWindow return null on topwindow TEST-PASS | tests/test-tab.test GetTabForWindow | getTabForWindow return null on topwindow TEST-PASS | tests/test-tab.test GetTabForWindow | We are able to find the tab with his content window object TEST-PASS | tests/test-tab.test GetTabForWindow | We are able to find the tab with an iframe window object TEST-PASS | tests/test-tab.test GetTabForWindow | We are able to find the tab with a sub-iframe window object TEST-PASS | tests/test-tab.test GetTabForWindow | We are able to find the tab with a sub-sub-iframe window object TEST-PASS | tests/test-tab.test GetTabForWindow | We get the correct tab even when it's in the background System JS : ERROR resource:///modules/NetworkPrioritizer.jsm:75 - TypeError: aBrowser is null JavaScript error: chrome://browser/content/browser.js, line 7232: value is not a non-null object TEST-END | tests/test-tab.test GetTabForWindow TEST-START | tests/test-tab.test behavior on close TEST-INFO | [JavaScript Error: "aBrowser is null" {file: "resource:///modules/NetworkPrioritizer.jsm" line: 75}] TEST-UNEXPECTED-FAIL | tests/test-tab.test behavior on close | Test output exceeded timeout (300s). Traceback (most recent call last): File "jetpack/bin/cfx", line 33, in <module> cuddlefish.run() File "/builds/slave/talos-slave/test/build/jetpack/python-lib/cuddlefish/__init__.py", line 612, in run test_all_packages(env_root, defaults=options.__dict__) File "/builds/slave/talos-slave/test/build/jetpack/python-lib/cuddlefish/__init__.py", line 494, in test_all_packages env_root=env_root) File "/builds/slave/talos-slave/test/build/jetpack/python-lib/cuddlefish/__init__.py", line 945, in run pkgdir=options.pkgdir) File "/builds/slave/talos-slave/test/build/jetpack/python-lib/cuddlefish/runner.py", line 742, in run_app OUTPUT_TIMEOUT, test_name, parseable) Exception: Test output exceeded timeout (300s).

We haven't seen this in a year.