pexpect: TIMEOUT no longer clears child.before

[Adrian Casey]

The behaviour of pexpect has changed between version 2.1 and 2.3.  In 
version 2.1, the following code would result in child.before being 
cleared -:

 >>>child.expect(pexpect.TIMEOUT,1)
 

In version 2.3, this is no longer the case.  No matter how many times 
the above code is run, child.before continues to hold the output from 
previous commands.  It is important to be able to clear the contents of 
child.before between each command.  What is the correct way to do this 
in version 2.3?

Adrian.