What does a build config mean in this case? Previous builds are available from master and builder name.

(sorry for the unclear description)

A build config means the combination of master name and builder name.

Currently on buildbot, there is build number, so we could use master/builder and build number to query previous builds.

After migration to Luci, per discussion with iannucci@, the concept of build number will be gone and build id (a uuid or hash?) will be in place. So we need a new mechanism to go from one build to its previous build.
Is an API already existing?

If this is really a Pri-1, find an owner and update the priority.

This is the result of a bulk edit that moved high priority available bugs to a lower priority in an attempt to be more honest with bug filers.

The following revision refers to this bug:
  https://chromium.googlesource.com/external/github.com/luci/luci-go.git/+/9fb9880d65325cef1fd8ff4099a1de27b4bf684e

commit 9fb9880d65325cef1fd8ff4099a1de27b4bf684e
Author: hinoka <hinoka@google.com>
Date: Thu Apr 20 22:17:27 2017

Milo buildbot builder page: Add pagnation with cursors.

In the UI, backward pages are implemented via memcache, just like luci scheduler
In the API, backward pages are not supported

Note that for the most part we operate around pointers to cursors, to store the state that "the cursor does not exist", ie the end of the query has been reached.

BUG= 679931 , 700263 

Review-Url: https://codereview.chromium.org/2810113002

[modify] https://crrev.com/9fb9880d65325cef1fd8ff4099a1de27b4bf684e/milo/api/proto/buildbot.pb.go
[modify] https://crrev.com/9fb9880d65325cef1fd8ff4099a1de27b4bf684e/milo/api/proto/buildbot.proto
[modify] https://crrev.com/9fb9880d65325cef1fd8ff4099a1de27b4bf684e/milo/api/proto/pb.discovery.go
[modify] https://crrev.com/9fb9880d65325cef1fd8ff4099a1de27b4bf684e/milo/api/resp/builder.go
[modify] https://crrev.com/9fb9880d65325cef1fd8ff4099a1de27b4bf684e/milo/appengine/buildbot/builder.go
[modify] https://crrev.com/9fb9880d65325cef1fd8ff4099a1de27b4bf684e/milo/appengine/buildbot/console.go
[modify] https://crrev.com/9fb9880d65325cef1fd8ff4099a1de27b4bf684e/milo/appengine/buildbot/datastore.go
[modify] https://crrev.com/9fb9880d65325cef1fd8ff4099a1de27b4bf684e/milo/appengine/buildbot/grpc.go
[modify] https://crrev.com/9fb9880d65325cef1fd8ff4099a1de27b4bf684e/milo/appengine/buildbot/html.go
[modify] https://crrev.com/9fb9880d65325cef1fd8ff4099a1de27b4bf684e/milo/appengine/common/funcs.go
[modify] https://crrev.com/9fb9880d65325cef1fd8ff4099a1de27b4bf684e/milo/appengine/common/middleware.go
[modify] https://crrev.com/9fb9880d65325cef1fd8ff4099a1de27b4bf684e/milo/appengine/frontend/expectations/buildbot.builder-Basic_Test_no_builds.html
[modify] https://crrev.com/9fb9880d65325cef1fd8ff4099a1de27b4bf684e/milo/appengine/frontend/expectations/buildbot.builder-Basic_Test_with_builds.html
[modify] https://crrev.com/9fb9880d65325cef1fd8ff4099a1de27b4bf684e/milo/appengine/frontend/templates/pages/builder.html

buildbucket search API can be used to query build history in LUCI. This is where Milo loads builds from.

This applies to waterfalls too, but we didn't migrate any waterfalls to buildbucket yet.

This request looks already fulfilled to me, so marking as fixed.