Stab-in-the-dark error fix for the crashing windows tinderboxes. Helps win2 anyways.

src/comp/middle/resolve.rs

@@ -689,8 +689,10 @@ fn in_scope(e: &env, sp: &span, name: &ident, s: &scope, ns: namespace) ->
           }
           scope_arm(a) {
             if ns == ns_value {
-                ret option::map(ast::def_binding,
-                                lookup_in_pat(name, a.pats[0]));
+                alt lookup_in_pat(name, a.pats[0]) {
+                  some(did) { ret some(ast::def_binding(did)); }
+                  _ { ret none }
+                }
             }
           }
         }