The "gating.yaml" is fetched from git repo based on the URL of a specific build
in Koji.
The file is fetched from specific git commit (the revision is part of the build URL).
More specifically:
1. Greewave gets the build data "koji call getBuild $NVR",
2. parses URL in "source" field [1] and
3. constructs the "gating.yaml" URL based on DIST_GIT_URL_TEMPLATE specified in
Greenwave configuration. [2]
[1] We need namespace ("rpms" or "containers" etc.), git revision and
package name (or rather git repository name).
[2] The URL template is something like
"{DIST_GIT_BASE_URL}/{pkg_namespace}/{pkg_name}/raw/{rev}/f/gating.yaml".