* bzrlib/tests/test_http.py: (TestRangeRequestServer): New class implementing tests involving range requests. (TestSingleRangeRequestServer, TestSingleRangeRequestServer_urllib, TestSingleRangeRequestServer_pycurl, TestNoRangeRequestServer, TestNoRangeRequestServer_urllib, TestNoRangeRequestServer_pycurl):New classes testing http transports behavior against bogus range request handling servers.
* bzrlib/tests/__init__.py: (TestCase.assertListRaises): Gratefully accepted from bzrlib/tests/test_transport_implementations.py
* bzrlib/tests/test_transport_implementations.py: (TransportTests.test_has.assertListRaises): Generously given to bzrlib/tests/__init__.py.
* bzrlib/tests/HTTPTestUtil.py: (SingleRangeRequestHandler): New class implementing a server that handle only range requests by bogusly returning only the first requested range. (NoRangeRequestHandler): New class implementing a server that silently ignores range requests.