This patch adds the top-level `overrides` entry, which is used to
override (or pin) the refspec of repositories. The main difference to a
direct override is that this logic only applies to repos that are
already defined. By that, a superset of all repos can be added to this
entry (similar to a global lockfile), but only the currently active ones
are affected. A new top-level keyword is required because everything
below the "repos" keyword is potentially defined by "default" values.
For the locking mechanism, a clear separation between overrides (only
override if existing) and definitions is required to be able to define a
global lockfile with all possible repos, while just defining some repos.
Proposed-by: Ross Burton <ross@burtonini.com>
Signed-off-by: Felix Moessbauer <felix.moessbauer@siemens.com>
[Jan: also bump __file_version__]
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>