BuildBot: Add anchors for unbound aliases.

BuildBot: Add anchors for unbound aliases.

Currently, aliases only attach themselves to logs/links that reference
them. If those logs/links disappear, the alias is not shown. This change
makes it so that aliases without log/link anchors will generate link
anchors. This solves the problem of log aliase disappearing when the
logs are pruned from the master.

BUG=chromium:602384
TEST=local
  - Created aliased builds, deleted logs, still render.

R=estaab@chromium.org, iannucci@chromium.org, martiniss@chromium.org, sergiyb@chromium.org

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=300424

[dnj, 2016-04-13 15:40:00]

https://codereview.chromium.org/1885033002/diff/1/masters/master.chromium/tem...
File masters/master.chromium/templates/build.html (right):

https://codereview.chromium.org/1885033002/diff/1/masters/master.chromium/tem...
masters/master.chromium/templates/build.html:154: <span>{{ l.name }}</span>
(Will never be hit for scenario (2), since waterfall will need to be restarted
to emit empty links.)

https://codereview.chromium.org/1885033002/diff/1/third_party/buildbot_8_4p1/...
File third_party/buildbot_8_4p1/buildbot/status/web/build.py (right):

https://codereview.chromium.org/1885033002/diff/1/third_party/buildbot_8_4p1/...
third_party/buildbot_8_4p1/buildbot/status/web/build.py:155: 
Note: because templates are immediately loaded post-sync, but this code won't be
loaded before restart, there are 4 scenarios here:

1) Waterfall has old (before-alias) template, so it doesn't know about alises.
In this case, it will render links.
1a) If there are aliases (e.g., it's running a recipe/Annotee that emits them),
this new code will cause empty links to be emitted.
1b) If there are no aliases, this code will not run and nothing will be
different. It will show "- no logs -" like normal.

2) Waterfall has new templates (sync), but hasn't been restarted. This will not
affect them, as they will not generate empty links, so the new template code
will not be hit.
3) Waterfall has new templates and has been restarted. This will cause them to
generate empty links, which will be rendered as link-less anchors.

It should be noted that (1b) is not something that should happen. This is
because any waterfall that runs code that generates aliases should have their
templates updated to render aliases. AFAIK only internal waterfalls have not had
these updates. If, however, aliases are generated, nothing bad will happen, as
per (1b).

[Sergiy Byelozyorov, 2016-04-13 17:31:14]

lgtm

[dnj, 2016-05-03 04:40:31]

The CQ bit was checked by dnj@chromium.org

[commit-bot: I haz the power, 2016-05-03 04:40:45]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1885033002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1885033002/1

[commit-bot: I haz the power, 2016-05-03 04:45:02]

Description was changed from

==========
BuildBot: Add anchors for unbound aliases.

Currently, aliases only attach themselves to logs/links that reference
them. If those logs/links disappear, the alias is not shown. This change
makes it so that aliases without log/link anchors will generate link
anchors. This solves the problem of log aliase disappearing when the
logs are pruned from the master.

BUG=chromium:602384
TEST=local
  - Created aliased builds, deleted logs, still render.

R=estaab@chromium.org, iannucci@chromium.org, martiniss@chromium.org,
sergiyb@chromium.org
==========

to

==========
BuildBot: Add anchors for unbound aliases.

Currently, aliases only attach themselves to logs/links that reference
them. If those logs/links disappear, the alias is not shown. This change
makes it so that aliases without log/link anchors will generate link
anchors. This solves the problem of log aliase disappearing when the
logs are pruned from the master.

BUG=chromium:602384
TEST=local
  - Created aliased builds, deleted logs, still render.

R=estaab@chromium.org, iannucci@chromium.org, martiniss@chromium.org,
sergiyb@chromium.org

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=300424
==========

[commit-bot: I haz the power, 2016-05-03 04:45:03]

Committed patchset #1 (id:1) as
http://src.chromium.org/viewvc/chrome?view=rev&revision=300424