Deferreds are Beautiful documentation has incorrect output

New submission from ezyang <None>:

In "Exceptions will only be handled by errbacks", the ostensible output is:

{{{
callback 1
        got result: success
        about to raise exception
errback
we got an exception: Traceback (most recent call last):
  File "./deferred_ex2.py", line 85, in ?
    nonDeferredExample("success")
--- <exception caught here> ---
  File "./deferred_ex2.py", line 46, in nonDeferredExample
    result = failAtHandlingResult(result)
  File "./deferred_ex2.py", line 35, in failAtHandlingResult
    raise RuntimeError, "whoops! we encountered an error"
exceptions.RuntimeError: whoops! we encountered an error
}}}

This doesn't actually make much sense, since nonDeferredExample is a non-existent function in the code.

The real output should look something like:

{{{
callback 1
	got result: success
	about to raise exception
errback
we got an exception: Traceback (most recent call last):
  File "deferred_ex2.py", line 85, in <module>
    behindTheScenes("success")
--- <exception caught here> ---
  File "deferred_ex2.py", line 46, in behindTheScenes
    result = failAtHandlingResult(result)
  File "deferred_ex2.py", line 35, in failAtHandlingResult
    raise RuntimeError, "whoops! we encountered an error"
exceptions.RuntimeError: whoops! we encountered an error


-------------------------------------------------

callback 1
	got result: success
	about to raise exception
errback
we got an exception: Traceback (most recent call last):
  File "deferred_ex2.py", line 88, in <module>
    deferredExample()
  File "deferred_ex2.py", line 81, in deferredExample
    d.callback("success")
  File "/usr/lib/python2.6/dist-packages/twisted/internet/defer.py", line 243, in callback
    self._startRunCallbacks(result)
  File "/usr/lib/python2.6/dist-packages/twisted/internet/defer.py", line 312, in _startRunCallbacks
    self._runCallbacks()
--- <exception caught here> ---
  File "/usr/lib/python2.6/dist-packages/twisted/internet/defer.py", line 328, in _runCallbacks
    self.result = callback(self.result, *args, **kw)
  File "deferred_ex2.py", line 35, in failAtHandlingResult
    raise RuntimeError, "whoops! we encountered an error"
exceptions.RuntimeError: whoops! we encountered an error
}}}

Although I'm a little confused why the sample wants to run itself twice.

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Type     : defect
Component: core
Keywords : 
Priority : normal
Nosy     : 
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http://twistedmatrix.com/trac/ticket/3941