Validation of YANG leafref within union does not work

[olofhagsand]

Suppose one has the following yang:

container a {
   leaf ref {
     type reftype;
   }
  list b {
    key c;
    leaf c;
 }
}

And the following CLI commands:

cli> set a b x
cli> set a ref y
error: validation fail

This works, if reftype is:

 typedef reftype {
            type leafref {
                path "/a/b/c";
            }
  }

But the following does not work (validation does not fail)if reftype is a leafref within a union:

typedef reftype {
       type union {
               type string {
                   pattern 'default';
               }
               type leafref {
                   path "/a/b/c";
               }
           }
}