It's very common for consumers to perform some action on each
attempt iteration; for example logging a message that the operation
failed and a retry will be performed after some time. While this can
be done today using a custom wait_func, it's inconvenient to use
a partial to wrap an existing retrying sleep function just to get this
behavior.

This patch adds support for a new kwarg called wait_event_func
that when passed should reference a function to be called
before sleeping for another attempt iteration. This function
looks similar to retrying wait_funcs except its first arg is
the time to sleep as returned by the current 'wait' function.

A handful of unit tests are also included.

It's very common for consumers to perform some action on each
attempt iteration; for example logging a message that the operation
failed and a retry will be performed after some time. While this can
be done today using a custom wait_func, it's inconvenient to use
a partial to wrap an existing retrying sleep function just to get this
behavior.

This patch adds support for a new kwarg called wait_event_func
that when passed should reference a function to be called
before sleeping for another attempt iteration. This function
looks similar to retrying wait_funcs except its first arg is
the time to sleep as returned by the current 'wait' function.

A handful of unit tests are also included.

No assertIsNotNone() in py26 so change to a py26 compatible assert statement.

…nto retry_log_hook

Conflicts:
	test_retrying.py

Conflicts:
	AUTHORS.rst
	retrying.py
	test_retrying.py