Fixed late binding of url_prefix. This fixes #29.

flask.py

@@ -448,7 +448,7 @@ def add_url_rule(self, rule, endpoint, view_func=None, **options):
         """
         def register_rule(state):
             the_rule = rule
-            if self.url_prefix:
+            if state.url_prefix:
                 the_rule = state.url_prefix + rule
             state.app.add_url_rule(the_rule, '%s.%s' % (self.name, endpoint),
                                    view_func, **options)

tests/flask_tests.py

@@ -441,6 +441,15 @@ def index():
         assert catched == ['before-app', 'before-admin',
                            'after-admin', 'after-app']
 
+    def test_late_binding(self):
+        app = flask.Flask(__name__)
+        admin = flask.Module(__name__, 'admin')
+        @admin.route('/')
+        def index():
+            return '42'
+        app.register_module(admin, url_prefix='/admin')
+        assert app.test_client().get('/admin/').data == '42'
+
 
 def suite():
     from minitwit_tests import MiniTwitTestCase