Fix delete_if (reject!) for the STL container wrappers.

Previously they would sometimes seg fault or not work.

Lib/ruby/std_set.i

@@ -152,10 +152,29 @@
   }
 %}
 
+%define %swig_sequence_methods_extra_set(Sequence...)
+  %extend {
+    %alias reject_bang "delete_if";
+    Sequence* reject_bang() {
+      if ( !rb_block_given_p() )
+	rb_raise( rb_eArgError, "no block given" );
+
+      for ( Sequence::iterator i = $self->begin(); i != $self->end(); ) {
+        VALUE r = swig::from< Sequence::value_type >(*i);
+        Sequence::iterator current = i++;
+        if ( RTEST( rb_yield(r) ) )
+          $self->erase(current);
+      }
+
+      return self;
+    }
+  }
+%enddef
 
 %define %swig_set_methods(set...)
 
   %swig_sequence_methods_common(%arg(set));
+  %swig_sequence_methods_extra_set(%arg(set));
 
   %fragment("RubyPairBoolOutputIterator","header",fragment=SWIG_From_frag(bool),fragment="RubySequence_Cont") {}