See all the red boxes on https://codereview.chromium.org/1937093002/ patch set 1.

Mentions go, variable bots, findit, so cc'ing someone from each of these.

E.g.

https://build.chromium.org/p/tryserver.chromium.win/builders/win_chromium_variable/builds/187

Running recipe with {u'recipe': 'findit/chromium/compile', u'patch_project': u'chromium', u'buildnumber': 187, u'slavename': u'vm185-m4', u'blamelist': [u'markdittmer@chromium.org'], u'branch': u'', u'master': u'tryserver.chromium.win', u'patchset': 1, u'issue': 1937093002, u'revision': u'', u'workdir': u'E:\\b\\build\\slave/win', u'repository': u'', u'buildername': u'win_chromium_variable', u'patch_storage': u'rietveld', u'mastername': u'tryserver.chromium.win', u'buildbucket': u'{"build": {"bucket": "master.tryserver.chromium.win", "created_by": "user:markdittmer@chromium.org", "created_ts": "1462201885076570", "id": "9013763912945638192", "lease_key": "1116922538", "tags": ["builder:win_chromium_variable", "buildset:patch/rietveld/codereview.chromium.org/1937093002/1", "master:tryserver.chromium.win", "user_agent:rietveld"]}}', u'requester': u'markdittmer@chromium.org', u'buildbotURL': u'http://build.chromium.org/p/tryserver.chromium.win/', u'build_data_dir': u'E:\\b\\build\\slave\\win\\build\\.recipe_runtime\\tmp5a0fow\\build_data', u'rietveld': u'https://codereview.chromium.org', u'project': u'', u'requestedAt': 1462201889}
@@@STEP_TEXT@<br/>running recipe: "findit/chromium/compile"@@@
@@@STEP_CLOSED@@@
@@@SEED_STEP@Uncaught Exception@@@
@@@STEP_CURSOR@Uncaught Exception@@@
@@@STEP_STARTED@@@
@@@STEP_LINK@stdout-->stdio@https://luci-logdog.appspot.com/v/?s=bb%2Ftryserver.chromium.win%2Fwin_chromium_variable%2F187%2F%2B%2Frecipes%2Fsteps%2FUncaught_Exception%2F0%2Fstdout@@@
@@@STEP_LOG_LINE@exception@Traceback (most recent call last):@@@
@@@STEP_LINK@logdog-->exception@https://luci-logdog.appspot.com/v/?s=bb%2Ftryserver.chromium.win%2Fwin_chromium_variable%2F187%2F%2B%2Frecipes%2Fsteps%2FUncaught_Exception%2F0%2Flogs%2Fexception%2F0@@@
@@@STEP_LOG_LINE@exception@  File "E:\b\build\scripts\slave\.recipe_deps\recipe_engine\recipe_engine\run.py", line 397, in run@@@
@@@STEP_LOG_LINE@exception@    recipe_result = recipe_script.run(api, api._engine.properties)@@@
@@@STEP_LOG_LINE@exception@  File "E:\b\build\scripts\slave\.recipe_deps\recipe_engine\recipe_engine\loader.py", line 57, in run@@@
@@@STEP_LOG_LINE@exception@    self.RunSteps, properties, self.PROPERTIES, api=api)@@@
@@@STEP_LOG_LINE@exception@  File "E:\b\build\scripts\slave\.recipe_deps\recipe_engine\recipe_engine\loader.py", line 512, in invoke_with_properties@@@
@@@STEP_LOG_LINE@exception@    **additional_args)@@@
@@@STEP_LOG_LINE@exception@  File "E:\b\build\scripts\slave\.recipe_deps\recipe_engine\recipe_engine\loader.py", line 471, in _invoke_with_properties@@@
@@@STEP_LOG_LINE@exception@    prop_name, PROPERTY_SENTINEL)))@@@
@@@STEP_LOG_LINE@exception@  File "E:\b\build\scripts\slave\.recipe_deps\recipe_engine\recipe_engine\recipe_api.py", line 616, in interpret@@@
@@@STEP_LOG_LINE@exception@    self.name, self.__property_type, self.module))@@@
@@@STEP_LOG_LINE@exception@ValueError: No default specified and no value provided for 'target_mastername' from recipe 'target_mastername'@@@
@@@STEP_LOG_END@exception@@@
@@@STEP_CLOSED@@@
panic: process returned negative return code (-1)

goroutine 1 [running]:
panic(0x5de760, 0x10f62b78)
	E:/b/build/slave/infra-continuous/build/golang/go/src/runtime/panic.go:464 +0x326
github.com/luci/luci-go/client/logdog/annotee/executor.(*Executor).Run.func1(0x10e628d0, 0x10e70780, 0x224928, 0x10ed8760)
	E:/b/build/slave/infra-continuous/build/infra/go/src/github.com/luci/luci-go/client/logdog/annotee/executor/executor.go:106 +0x240
github.com/luci/luci-go/client/logdog/annotee/executor.(*Executor).Run(0x10e70780, 0x224928, 0x10ed8760, 0x10e686e0, 0x8, 0x9, 0x0, 0x0)
	E:/b/build/slave/infra-continuous/build/infra/go/src/github.com/luci/luci-go/client/logdog/annotee/executor/executor.go:146 +0xb96
main.mainImpl(0x10e686e0, 0x8, 0x9, 0x5a4740)
	E:/b/build/slave/infra-continuous/build/infra/go/src/github.com/luci/luci-go/client/cmd/logdog_annotee/main.go:207 +0xd46
main.main()
	E:/b/build/slave/infra-continuous/build/infra/go/src/github.com/luci/luci-go/client/cmd/logdog_annotee/main.go:229 +0x54
[E 2016-05-02T08:13:43.091-07:00 3112 subcommand_run.go:262] Command failed.                             {"exitStatus":2}
[I 2016-05-02T08:13:43.216-07:00 3112 main.go:335] Terminating.                                {"returnCode":2}
RemoveDirectory running cmd.exe /c rd /q /s e:\b\build\slave\win\build\.recipe_runtime

Not sure why these try jobs ran at all.