add "upstream" stable-branch-type

Add a stable-branch-type called "upstream" for projects that follow
the naming conventions of another upstream project (see puppet-ceph
for an example).

Change-Id: I354bf975311c2b02c020dc83590c041c7733b041
Signed-off-by: Doug Hellmann <doug@doughellmann.com>

README.rst

@@ -432,6 +432,10 @@ The top level of a deliverable file is a mapping with keys:
     hash. This mode should only be used for projects that do not tag
     releases, such as devstack and grenade.
 
+  ``upstream``
+    Stable branch names track upstream release names, rather than
+    OpenStack series names.
+
 ``branches``
   A list of the branches for the deliverable.
 

openstack_releases/cmds/validate.py

@@ -681,11 +681,22 @@ def validate_stable_branches(deliverable_info, workdir,
                          'does not exist' % (
                              (loc, repo, branch['name'])))
                     )
+        elif branch_mode == 'upstream':
+            if not isinstance(location, six.string_types):
+                mk_error(
+                    ('branch location for %s is '
+                     'expected to be a string but got a %s' % (
+                         branch['name'], type(location)))
+                )
         else:
             mk_error(
                 ('unrecognized stable-branch-type %r' % (branch_mode,))
             )
-        if series_name == '_independent':
+        if branch_mode == 'upstream':
+            mk_warning(
+                'skipping branch name check for upstream mode'
+            )
+        elif series_name == '_independent':
             if series not in known_series:
                 mk_error(
                     ('stable branches must be named for known series '

openstack_releases/schema.yaml

@@ -38,7 +38,7 @@ properties:
     enum: [ "std", "xstatic", "fuel" ]
   stable-branch-type:
     type: "string"
-    enum: [ "std", "tagless" ]
+    enum: [ "std", "tagless", "upstream" ]
   releases:
     type: "array"
     items: