Fix is here

(master)
https://chromium-review.googlesource.com/c/chromiumos/chromite/+/738869

(cherry-picked to R63)
https://chromium-review.googlesource.com/c/chromiumos/chromite/+/738674

Luckily, the profiles for R63 and R64 are the same for now.

The automation is using the chrome branch in place of the ChromeOS milestone?
I know that they should track each other closely, but I've seen cases where they are not equal.
The branch number that I include in the profile names is the ChromeOS milestone.

The build system doesn't know the CrOS milestone it is building for?

It looks to me that version_info.chrome_branch is the Chrome OS milestone:
https://cs.corp.google.com/chromeos_public/chromite/cbuildbot/stages/report_stages.py?type=cs&q=CHROME_BRANCH&l=438

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/chromite/+/aa0da89d125cedfb7933fb38840e13e43a0a0d9c

commit aa0da89d125cedfb7933fb38840e13e43a0a0d9c
Author: Ting-Yuan Huang <laszio@chromium.org>
Date: Thu Oct 26 04:59:02 2017

kernel_afdo: cast chrome_version to int

It was passed to afdo.FindLatestProfile in string. Because,
for example, '63' > 64 in python (str > int), FindLatestProfile
always returns the profile of latest Chrome branch.

BUG= chromium:778460 
TEST=cros tryjob master-chrome-pfq

Change-Id: Ie0bbb38604aa20a6d095002d30b728270ea17a5b
Reviewed-on: https://chromium-review.googlesource.com/738869
Commit-Ready: Ting-Yuan Huang <laszio@chromium.org>
Tested-by: Ting-Yuan Huang <laszio@chromium.org>
Reviewed-by: Luis Lozano <llozano@chromium.org>

[modify] https://crrev.com/aa0da89d125cedfb7933fb38840e13e43a0a0d9c/cbuildbot/stages/afdo_stages.py

cbuildbot should have access to all the version fields as it exists in the tree:
  https://chromium.googlesource.com/chromiumos/overlays/chromiumos-overlay/+/master/chromeos/config/chromeos_version.sh

look at the GetVersionInfo helper which returns a VersionInfo object which has both the Chrome and Chrome OS version components.

(which is what the code in question is doing already)

The following revision refers to this bug:
  https://chromium.googlesource.com/chromiumos/chromite/+/9bb6df2b7dd45b68c481f698bce312383e46d2ae

commit 9bb6df2b7dd45b68c481f698bce312383e46d2ae
Author: Ting-Yuan Huang <laszio@chromium.org>
Date: Thu Oct 26 17:33:32 2017

kernel_afdo: cast chrome_version to int

It was passed to afdo.FindLatestProfile in string. Because,
for example, '63' > 64 in python (str > int), FindLatestProfile
always returns the profile of latest Chrome branch.

BUG= chromium:778460 
TEST=cros tryjob master-chrome-pfq

Change-Id: Ie0bbb38604aa20a6d095002d30b728270ea17a5b
Reviewed-on: https://chromium-review.googlesource.com/738674
Reviewed-by: Ting-Yuan Huang <laszio@chromium.org>
Tested-by: Ting-Yuan Huang <laszio@chromium.org>

[modify] https://crrev.com/9bb6df2b7dd45b68c481f698bce312383e46d2ae/cbuildbot/stages/afdo_stages.py

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