Patch by Piotr Szczepaniak.

* Use context manager on urllib objects to ensure that they are closed on error
* Use self.addCleanup() to cleanup resources even if a test is interrupted
  with CTRL+c

This backports a patch by Victor Stinner.

Initial patch by Hans Lawrenz.

Patch by Johannes Ebke.

Thanks to Ville Skyttä for the patch.

attributes.

attributes.

new exception with setting current exception as __cause__.

_PyErr_FormatFromCause(exception, format, args...) is equivalent to Python

    raise exception(format % args) from sys.exc_info()[1]

new exception with setting current exception as __cause__.

_PyErr_FormatFromCause(exception, format, args...) is equivalent to Python

    raise exception(format % args) from sys.exc_info()[1]

Patch by Mariatta Wijaya.

Patch by Mariatta Wijaya.