Perhaps we should preserve the order in the config. Can be done by adding “Ordinal int” field to Console entity. 

Issue 790834 has been merged into this issue.

The following revision refers to this bug:
  https://chromium.googlesource.com/infra/luci/luci-go.git/+/fbcd6e0de08a8f044ccb7dc0dec4c3f561766ed6

commit fbcd6e0de08a8f044ccb7dc0dec4c3f561766ed6
Author: Jao-ke Chin-Lee <jchinlee@chromium.org>
Date: Mon Dec 04 22:37:21 2017

[milo] Prepare to support ordered builder groups.

Builder group order matches order of specification in the
config. This CL does not surface the ordering in the UI.

Bug:  787283 
Change-Id: I07da77fa3a280a422e819509f7f873c46622a799
Reviewed-on: https://chromium-review.googlesource.com/807164
Commit-Queue: Jao-ke Chin-Lee <jchinlee@chromium.org>
Reviewed-by: Ryan Tseng <hinoka@chromium.org>
Reviewed-by: Nodir Turakulov <nodir@chromium.org>

[modify] https://crrev.com/fbcd6e0de08a8f044ccb7dc0dec4c3f561766ed6/milo/common/config.go
[modify] https://crrev.com/fbcd6e0de08a8f044ccb7dc0dec4c3f561766ed6/milo/common/config_test.go

The following revision refers to this bug:
  https://chromium.googlesource.com/infra/luci/luci-go.git/+/e137a647b374734bcd0a6904b23389de95126d12

commit e137a647b374734bcd0a6904b23389de95126d12
Author: Jao-ke Chin-Lee <jchinlee@chromium.org>
Date: Tue Dec 05 00:57:13 2017

[milo] Surface ordered builder groups.

Bug:  787283 
Change-Id: I136cb459540e475ba19d66c3dea7d40763b48e75
Reviewed-on: https://chromium-review.googlesource.com/807354
Reviewed-by: Nodir Turakulov <nodir@chromium.org>
Commit-Queue: Jao-ke Chin-Lee <jchinlee@chromium.org>

[modify] https://crrev.com/e137a647b374734bcd0a6904b23389de95126d12/milo/common/config.go
[modify] https://crrev.com/e137a647b374734bcd0a6904b23389de95126d12/milo/common/config_test.go