Missed one weaken() in the wrong place

lib/EnsEMBL/REST/Model/ga4gh/variantSet.pm

@@ -31,7 +31,8 @@ has 'context' => (is => 'ro');
 
 sub build_per_context_instance {
   my ($self, $c, @args) = @_;
-  return $self->new({ context => weaken($c), %$self, @args });
+  weaken($c);
+  return $self->new({ context => $c, %$self, @args });
 }
 
 sub fetch_ga_variantSet {