Handle cases where current block being processed is only in the...

Handle cases where current block being processed is only in the blocks_reversible table (avoid returning 0 for a block).

(cherry picked from commit 39cc7c86)

Co-authored-by: Dan Notestein <dan@syncad.com>

src/hive_fork_manager/app_api.sql

@@ -882,10 +882,13 @@ CREATE OR REPLACE FUNCTION hive.get_app_current_block_age(_contexts hive.context
     STABLE
 AS $BODY$
 BEGIN
-    RETURN now() - (select min(coalesce(hafd.blocks.created_at, to_timestamp(0))) from
+    RETURN now() - (select min(coalesce(hafd.blocks.created_at, hafd.blocks_reversible.created_at, to_timestamp(0))) from
                     UNNEST(_contexts) AS context_names(name)
                     LEFT JOIN hafd.contexts USING(name)
-                    LEFT JOIN hafd.blocks on num = hafd.contexts.current_block_num);
+                    LEFT JOIN hafd.blocks on hafd.blocks.num = hafd.contexts.current_block_num
+                    LEFT JOIN hafd.blocks_reversible on hafd.blocks_reversible.num = hafd.contexts.current_block_num AND
+                                                        hafd.blocks_reversible.fork_id = hafd.contexts.fork_id
+                    );
 END;
 $BODY$;