deprecate the use of highlights attached to a release

We want teams to use reno for release notes and cycle-highlights for
more general notes. This patch disallows the use of release-specific
highlights for new releases from the new series with a message
explaining why. We can change the schema and let the yamllint perform
the check after running this way for a while.

Change-Id: I8e885b856f3412a3f6df691abbfd8c78037bcd91
Signed-off-by: Doug Hellmann <doug@doughellmann.com>

openstack_releases/cmds/validate.py

@@ -170,6 +170,21 @@ def validate_series_open(deliverable_info,
             expected_branch, previous_deliverable_file, series_name))
 
 
+def deprecate_release_highlights(deliverable_info,
+                                 mk_warning, mk_error):
+    "No releases in the new series until the previous one has a branch."
+    header('Deprecate Release Highlights')
+    if not deliverable_info.get('releases'):
+        return
+    last_release = deliverable_info['releases'][-1]
+    if 'highlights' in last_release:
+        mk_error(
+            'The per-release "highlights" feature is deprecated. '
+            'Please use "cycle-highlights" for marketing notes '
+            'and reno for release notes.'
+        )
+
+
 def validate_series_first(deliverable_info, series_name,
                           mk_warning, mk_error):
     "The first release in a series needs to end with '.0'."
@@ -1157,6 +1172,11 @@ def main():
                 mk_warning,
                 mk_error,
             )
+            deprecate_release_highlights(
+                deliverable_info,
+                mk_warning,
+                mk_error,
+            )
         validate_series_first(
             deliverable_info,
             series_name,