The PreCQ Launcher run that generated those builds:

https://uberchromegw.corp.google.com/i/chromeos/builders/pre-cq-launcher/builds/11125

The original description was incorrect.

The PreCQ did reject the CL correctly, but launched the tryjobs for it more than once.

Working to understand why.

The PreCQ launcher is not writing out "trybot_launching" actions to the CL Actions table.

From code inspection, it looks like the "cros tryjob" output is not being properly parsed for the buildbucket IDs of the tryjobs.

However, adding a unittest with a copy/paste of the output shows that it parses correctly, and inspection of the "cros tryjob" code shows that the relevant output is generated identically for both swarming and buildbot builds.

Nxia did a lot of testing, and the two of us think it's figured out. There was ANOTHER bug in my quick/dirty/temp hack. As she correctly pointed out, it should have had unittests, even if it's only for a couple days.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/chromite/+/f67bab4160f0c8cc2638292be515a117a755d5d7

commit f67bab4160f0c8cc2638292be515a117a755d5d7
Author: Don Garrett <dgarrett@google.com>
Date: Wed Mar 21 20:58:29 2018

precq_launcher: Fix swarming PreCQ hack.

It was just a stupid error. Fix it, to prove out the behavior in
production, then revert it all when we move PreCQ builders to
swarming.

Thanks nxia@ who found it!

BUG= chromium:823445 
TEST=run_tests

Change-Id: I4cf37b527d11520b8551322c7d76cd700dea9f95
Reviewed-on: https://chromium-review.googlesource.com/973807
Tested-by: Don Garrett <dgarrett@chromium.org>
Trybot-Ready: Don Garrett <dgarrett@chromium.org>
Reviewed-by: Ningning Xia <nxia@chromium.org>

[modify] https://crrev.com/f67bab4160f0c8cc2638292be515a117a755d5d7/cbuildbot/stages/sync_stages.py

Verified to work correctly with CL:*590929.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/d000ba8fdded914995828078611e361e96f7d722

commit d000ba8fdded914995828078611e361e96f7d722
Author: chromite-chromium-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com <chromite-chromium-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com>
Date: Thu Mar 22 03:25:05 2018

Roll src/third_party/chromite/ 1d37d531d..8bf5a7243 (3 commits)

https://chromium.googlesource.com/chromiumos/chromite.git/+log/1d37d531d536..8bf5a724397c

$ git log 1d37d531d..8bf5a7243 --date=short --no-merges --format='%ad %ae %s'
2018-03-20 manojgupta cbuildbot: Only build virtual/target-fuzzers for fuzzer builders.
2018-03-15 dgarrett archive_lib: Stop appending trybot- for tryjobs.
2018-03-21 dgarrett precq_launcher: Fix swarming PreCQ hack.

Created with:
  roll-dep src/third_party/chromite
BUG= chromium:823787 , chromium:667393 , chromium:823445 


The AutoRoll server is located here: https://chromite-chromium-roll.skia.org

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

If the roll is causing failures, please contact the current sheriff, who should
be CC'd on the roll, and stop the roller if necessary.


TBR=chrome-os-gardeners@chromium.org

Change-Id: I7abe614767178c4d769dd22efaa488e7e6e9083e
Reviewed-on: https://chromium-review.googlesource.com/974743
Reviewed-by: Chromite Chromium Autoroll <chromite-chromium-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com>
Commit-Queue: Chromite Chromium Autoroll <chromite-chromium-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#544964}
[modify] https://crrev.com/d000ba8fdded914995828078611e361e96f7d722/DEPS

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/chromite/+/57ebfa51e019b523345162bf08fdf30e93a52ce0

commit 57ebfa51e019b523345162bf08fdf30e93a52ce0
Author: Don Garrett <dgarrett@google.com>
Date: Thu Mar 22 20:20:17 2018

precq_launcher: Remove test swarming hack.

This change reverts most functionality from CL:967073 and CL:973807,
now that we have proven out that the PreCQ interacts correctly with
swarming builds, but leaves in the "swarming" option with a default of
False.

BUG= chromium:823445 
TEST=run_tests

Change-Id: If57fb85c8ae70f9c8b3ec17a3ebf3aea319a50e5
Reviewed-on: https://chromium-review.googlesource.com/974575
Tested-by: Don Garrett <dgarrett@chromium.org>
Trybot-Ready: Don Garrett <dgarrett@chromium.org>
Reviewed-by: Ningning Xia <nxia@chromium.org>
Commit-Queue: Don Garrett <dgarrett@chromium.org>

[modify] https://crrev.com/57ebfa51e019b523345162bf08fdf30e93a52ce0/cbuildbot/stages/sync_stages.py

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/2220a285e044aff754b00e07521f5513c2eb992e

commit 2220a285e044aff754b00e07521f5513c2eb992e
Author: chromite-chromium-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com <chromite-chromium-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com>
Date: Fri Mar 23 00:48:01 2018

Roll src/third_party/chromite/ 051b1952c..0fba0a0ea (2 commits)

https://chromium.googlesource.com/chromiumos/chromite.git/+log/051b1952ca4b..0fba0a0ea755

$ git log 051b1952c..0fba0a0ea --date=short --no-merges --format='%ad %ae %s'
2018-03-22 chrome-bot Update config settings by config-updater.
2018-03-21 dgarrett precq_launcher: Remove test swarming hack.

Created with:
  roll-dep src/third_party/chromite
BUG= chromium:823445 


The AutoRoll server is located here: https://chromite-chromium-roll.skia.org

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

If the roll is causing failures, please contact the current sheriff, who should
be CC'd on the roll, and stop the roller if necessary.


TBR=chrome-os-gardeners@chromium.org

Change-Id: I6f0e7c15763b852ee488fc76800040aca0e88f47
Reviewed-on: https://chromium-review.googlesource.com/976548
Reviewed-by: Chromite Chromium Autoroll <chromite-chromium-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com>
Commit-Queue: Chromite Chromium Autoroll <chromite-chromium-autoroll@skia-buildbots.google.com.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#545315}
[modify] https://crrev.com/2220a285e044aff754b00e07521f5513c2eb992e/DEPS