The build alert contains a URL of this form:

https://luci-milo.appspot.com/buildbot/chromiumos.tryserver/bluestreak-pre-cq/0

That link leads to a very old build that ran before swarming, and seems to include the builder_run number as an id.

We can now link to a build_config with a URL of the form:

https://cros-goldeneye.corp.google.com/chromeos/legoland/builderHistory?buildConfig=bluestreak-pre-cq

Or to a specific build via the buildbucket id with a URL of the form:

https://cros-goldeneye.corp.google.com/chromeos/healthmonitoring/buildDetails?buildbucketId=8948076123573774080