Add RequestError subclass to PoolError.

The former PoolError `__reduce__` method was broken as it assumed the `url`
attribute was set, when in fact it was not.

As per issue #174, this commit creates a `RequestError` subclass of `PoolError`
and makes `MaxRetryError` and TimeoutError` a subclass of `RequestError`.

1 files changed, 10 insertions, 2 deletions

diff --git a/test/test_exceptions.py b/test/test_exceptions.py
index 3e02ca68..2ecb523c 100644
--- a/test/test_exceptions.py
+++ b/test/test_exceptions.py
@@ -1,7 +1,8 @@
 import unittest
 import pickle
 
-from urllib3.exceptions import HTTPError, MaxRetryError, LocationParseError
+from urllib3.exceptions import (HTTPError, MaxRetryError, LocationParseError,
+                                ClosedPoolError, EmptyPoolError, TimeoutError)
 from urllib3.connectionpool import HTTPConnectionPool
 
 
@@ -15,5 +16,12 @@ class TestPickle(unittest.TestCase):
 
     def test_exceptions_with_objects(self):
         assert pickle.dumps(HTTPError('foo'))
-        assert pickle.dumps(MaxRetryError(HTTPConnectionPool('localhost'), '/', None))
+        assert pickle.dumps(MaxRetryError(HTTPConnectionPool('localhost'),
+                                          '/', None))
         assert pickle.dumps(LocationParseError('fake location'))
+        assert pickle.dumps(ClosedPoolError(HTTPConnectionPool('localhost'),
+                                         None))
+        assert pickle.dumps(EmptyPoolError(HTTPConnectionPool('localhost'),
+                                         None))
+        assert pickle.dumps(TimeoutError(HTTPConnectionPool('localhost'),
+                                         '/', None))