From 5da31f8af36012a4f76c3bd0d536ae107e0519b5 Mon Sep 17 00:00:00 2001
From: Christian Becker <christian@dabecka.de>
Date: Wed, 15 Jul 2015 01:20:39 +0200
Subject: [PATCH 1/2] fix UnboundLocalError in handle_url_build_error

- caused by changes in the execution model of python 3 where the alias of an except clause is cleared on exit of the except
---
 flask/app.py             |  5 +++--
 flask/testsuite/basic.py | 11 +++++++++++
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/flask/app.py b/flask/app.py
index cc3fc1d9..e073798a 100644
--- a/flask/app.py
+++ b/flask/app.py
@@ -1631,8 +1631,9 @@ class Flask(_PackageBoundObject):
                 rv = handler(error, endpoint, values)
                 if rv is not None:
                     return rv
-            except BuildError as error:
-                pass
+            except BuildError as e:
+                # make error available outside except block (py3)
+                error = e
 
         # At this point we want to reraise the exception.  If the error is
         # still the same one we can reraise it with the original traceback,
diff --git a/flask/testsuite/basic.py b/flask/testsuite/basic.py
index 31fade13..803a008c 100644
--- a/flask/testsuite/basic.py
+++ b/flask/testsuite/basic.py
@@ -772,6 +772,17 @@ class BasicFunctionalityTestCase(FlaskTestCase):
         with app.test_request_context():
             self.assert_equal(flask.url_for('spam'), '/test_handler/')
 
+    def test_build_error_handler_reraise(self):
+        app = flask.Flask(__name__)
+
+        # Test a custom handler which reraises the BuildError
+        def handler_raises_build_error(error, endpoint, values):
+            raise error
+        app.url_build_error_handlers.append(handler_raises_build_error)
+
+        with app.test_request_context():
+            self.assertRaises(BuildError, flask.url_for, 'not.existing')
+
     def test_custom_converters(self):
         from werkzeug.routing import BaseConverter
         class ListConverter(BaseConverter):

From 765f851a7c880fc654eada6aefb4ce7aa5b14525 Mon Sep 17 00:00:00 2001
From: Markus Unterwaditzer <markus@unterwaditzer.net>
Date: Thu, 16 Jul 2015 12:01:25 +0200
Subject: [PATCH 2/2] Changelog for #1533

---
 CHANGES | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/CHANGES b/CHANGES
index a67937ff..89de874f 100644
--- a/CHANGES
+++ b/CHANGES
@@ -23,6 +23,8 @@ Version 0.10.2
 - Changed logic of before first request handlers to flip the flag after
   invoking.  This will allow some uses that are potentially dangerous but
   should probably be permitted.
+- Fixed Python 3 bug when a handler from `app.url_build_error_handlers`
+  reraises the `BuildError`.
 
 Version 0.10.1
 --------------