https://chromium-review.googlesource.com/#/c/340490/1 should fix it, we need a waterfall restart after it lands for it to go live (go/bug-a-trooper). 

If Lakitu is part of the release, why is it flagged as not important in the config? Can we land this CL on ToT so it does not get dropped in the future?

Lakitu is marked as important at ToT: https://chromium.googlesource.com/chromiumos/chromite/+/master/cbuildbot/chromeos_config.py#2538

For some reason the "important=True" got removed as part of the R51 builder setup CL: https://chromium-review.googlesource.com/#/c/338100/3/cbuildbot/chromeos_config.py

We have been getting release branch builds on the past few branches (R50, R49, ...).

What can we do from our side to prevent this from happening again?

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/chromite/+/52b065df8cec20059d6e73d83a6aeab32e70d106

commit 52b065df8cec20059d6e73d83a6aeab32e70d106
Author: Bernie Thompson <bhthompson@google.com>
Date: Sat Apr 23 04:24:00 2016

Make Lakitu configs important

BUG= chromium:606103 
TEST=None

Change-Id: I1056bf73472ca6b60a75747c51eaef8bced0aaf5
Reviewed-on: https://chromium-review.googlesource.com/340490
Reviewed-by: Amey Deshpande <ameyd@google.com>
Commit-Queue: Bernie Thompson <bhthompson@chromium.org>
Tested-by: Bernie Thompson <bhthompson@chromium.org>

[modify] https://crrev.com/52b065df8cec20059d6e73d83a6aeab32e70d106/cbuildbot/config_dump.json
[modify] https://crrev.com/52b065df8cec20059d6e73d83a6aeab32e70d106/cbuildbot/waterfall_layout_dump.txt
[modify] https://crrev.com/52b065df8cec20059d6e73d83a6aeab32e70d106/cbuildbot/chromeos_config.py

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/chromite/+/cf8757ca1a3f59404217455a505dbd25b5055aa4

commit cf8757ca1a3f59404217455a505dbd25b5055aa4
Author: Bernie Thompson <bhthompson@google.com>
Date: Sat Apr 23 18:26:01 2016

Remove lakitu_mobbuild configurations

The lakitu_mobbuild configuration is not being actively maintained,
so we can disable it.

BUG= chromium:606103 
TEST=None

Change-Id: I4ddc6f23820f5cc19ef6be9c553807c62814485f
Reviewed-on: https://chromium-review.googlesource.com/340500
Reviewed-by: Bernie Thompson <bhthompson@chromium.org>
Commit-Queue: Bernie Thompson <bhthompson@chromium.org>
Tested-by: Bernie Thompson <bhthompson@chromium.org>

[modify] https://crrev.com/cf8757ca1a3f59404217455a505dbd25b5055aa4/cbuildbot/config_dump.json
[modify] https://crrev.com/cf8757ca1a3f59404217455a505dbd25b5055aa4/cbuildbot/waterfall_layout_dump.txt
[modify] https://crrev.com/cf8757ca1a3f59404217455a505dbd25b5055aa4/cbuildbot/chromeos_config.py

https://chromium-review.googlesource.com/#/c/340490 looks to be merged already, but lakitu R51 builder has not started yet. What to do for the next step? We are supposed to cut a R51 release on Friday, and since Friday I have received more than 150 warning emails from our auto Jenkins testing complaining the latest image is missing.

We need https://bugs.chromium.org/p/chromium/issues/detail?id=606149, as soon as we can restart the waterfall the builders should go live. 

At the moment it seems we may be low on build machines so I cannot just restart it now, we need input from the infra team to reallocate machines, I suspect it will get restarted tomorrow. 

Waterfall restart succeeded, the lakitu builders are there and should run with the next R51 build (which is likely tomorrow morning).

I see a lakitu build has shown up on goldeneye already, so someone did a trybot release build?

In any case I think this is done, if the builders don't work on the next round for some reason that can be a new bug.

yes we forced a trybot on release branch in order to unblock testing on our end (which takes O(hours) after the image is available from buildbots).

will keep an eye on the release builders tomorrow.  thanks!

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/chromite/+/e8e860971a4732e7192e4cb09dc5fd6e7670ed8b

commit e8e860971a4732e7192e4cb09dc5fd6e7670ed8b
Author: Bernie Thompson <bhthompson@google.com>
Date: Sat Apr 23 18:32:00 2016

Remove lakitu_mobbuild configurations

The lakitu_mobbuild configuration is not being actively maintained,
so we can disable it.

BUG= chromium:606103 
TEST=None

Change-Id: I4ddc6f23820f5cc19ef6be9c553807c62814485f
Reviewed-on: https://chromium-review.googlesource.com/340502
Commit-Ready: Bernie Thompson <bhthompson@chromium.org>
Tested-by: Bernie Thompson <bhthompson@chromium.org>
Reviewed-by: Bernie Thompson <bhthompson@chromium.org>

[modify] https://crrev.com/e8e860971a4732e7192e4cb09dc5fd6e7670ed8b/cbuildbot/config_dump.json
[modify] https://crrev.com/e8e860971a4732e7192e4cb09dc5fd6e7670ed8b/cbuildbot/chromeos_config.py