negative integer for resized bytearray.

shelve.open() documentation was updated in f351fb7ea179.

This is a revertion of cfc66e37eb8e.

Thanks to 鄭景文 for the bug report. Thanks to Tin Tvrtković, Xiang
Zhang, and Dan McCombs for diagnosing the issue.

Based on patch by Gabriel Genellina.

Patch written by R. David Murray.

Patch by Martin Richard.  GH PR #365.

Patch by Richard Walker.

Patch by Manuel Kaufmann.

* tracing in the "u" mode now works
* trace_vdelete() with wrong mode no longer break tracing
* trace_vinfo() now always returns a list of pairs of strings

lazy-loaded module was already in sys.modules.

dictproxy was used in Python 2 and it was renamed to mappingproxy
in Python 3.3.

Patch by Julien.

Patch by Matt Morrison.

Several test cases in distutils use PyPIRCCommandTestCase as
their base class and as a result of that the following tests
were ran more than once:

* test_server_registration
* test_server_empty_registration
* test_config_interpolation

This commit moves the infrastructure used by other tests
into a new BasePyPIRCCommandTestCase class.