Merge branch '0.10-maintenance'

CHANGES

@@ -91,6 +91,8 @@ 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
 --------------

flask/app.py

@@ -1769,8 +1769,9 @@ class Flask(_PackageBoundObject):
                 rv = handler(error, endpoint, values)
                 if rv is not None:
                     return rv
-            except BuildError as error:
+            except BuildError as e:
-                pass
+                # 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,

tests/test_basic.py

@@ -1069,6 +1069,18 @@ def test_build_error_handler():
         assert flask.url_for('spam') == '/test_handler/'
 
 
+def test_build_error_handler_reraise():
+    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():
+        pytest.raises(BuildError, flask.url_for, 'not.existing')
+
+
 def test_custom_converters():
     from werkzeug.routing import BaseConverter