Attached is a patch that will fix this error, and also delete the png from memory when
finished with it. This way, if you are running this command multiple times, in a test
you will not keep data in memory you are no longer using.

That "del png" doesn't actually do anything in most cases, as the png variable is only
bound inside that function, which is about to end.

The one case I can think of in which it may have an effect is if you had an exception
that wasn't an IOError, so a traceback was generated, with the stack, so the stack
kept a reference to "png".  Then, I think, that "finally" clause would kick in and
remove "png" from that stack frame.

Fixed as of r9847

And now marking as fixed :)

keturn.keturn: no, once png is assigned, unless the mechanism that takes the screenshot
breaks - some object will always be assigned to 'png'. we catch an io error, but do
not `raise` an exception which would exit the program, and garbage collection would
clear the memory.

since we are returning True / False, we do need to clear png after its finished since
the function was written to not raise errors if the writing of the file should fail.
Also, screenshots can be pretty large depending on many factors, so its a good idea
to remove it as soon as we can determine whether we return true or false.