Merge pull request #449 from martinvanzijl/issue_426_fix_nullptr_when…

…_deleting_refs

Fix for issue #426. Fix null pointer when deleting refs.

src/main/java/org/kohsuke/github/GHRepository.java

@@ -813,7 +813,9 @@ public PagedIterable<GHRef> listRefs() throws IOException {
             public PagedIterator<GHRef> _iterator(int pageSize) {
                 return new PagedIterator<GHRef>(root.retrieve().asIterator(url, GHRef[].class, pageSize)) {
                     protected void wrapUp(GHRef[] page) {
-                        // no-op
+                        for(GHRef p: page) {
+                            p.wrap(root);
+                        }
                     }
                 };
             }