Thud branches required in certain repos?

[Andrew Geissler]

Recently we created a Thud branch (i.e. 2.6). Currently we've just branched
the openbmc/meta-* and openbmc/openbmc layers.

Pre repository CI (i.e. https://openpower.xyz/job/openbmc-repository-ci/) had
its scripts updated to support the new branch. Basically if a change comes in
from a branch, it will attempt to find and use that same branch from all of
the dependent repositories. If it can't find the branch, then it will just
use master from that build.

Dependent repositories are repositories that most repositories depend on and
are always built as a part of the per repository CI process:

  phosphor-objmgr
  sdbusplus
  sdeventplus
  gpioplus
  phosphor-logging
  phosphor-dbus-interfaces
  openpower-dbus-interfaces

In general, just using master from these dependent repositories will work. We
only run into issues if some sort of API or data type change occurs in master
that is not compatible with the branch.

To avoid weird errors in the future though, I'd like for the maintainers of the
above repos to create the corresponding branch in each of the above repos
whenever a new branch is created for the openbmc project.

Adding a branch is easy, just go to your project in gerrit and use the
"Create Branch" option. Be sure to put the "Initial Revision" commit at whatever
we were at when the Thud branch occurred and call it "thud".

Other ideas or thoughts?

Andrew