Fix bug in is-bounty-issue?, update docstring

resources/sql/queries.sql

@@ -358,7 +358,7 @@ WHERE issue_id = :issue_id;
 
 
 -- :name issue-exists :1
--- :doc updates issue's open status
+-- :doc returns true if given issue exists
 SELECT exists(SELECT 1
   FROM issues
   WHERE issue_id = :issue_id);

src/clj/commiteth/db/issues.clj

@@ -92,4 +92,7 @@
   [issue-id]
   (let [res (jdbc/with-db-connection [con-db *db*]
               (db/issue-exists con-db {:issue_id issue-id}))]
-    res))
+    (-> res
+        first
+        :exists
+        boolean)))