importable vomits entire file on closure built with inner lambda

[mmckerns]

There's a bug (I'm sure more than one) so that when you make a closure with a lambda as the inner function (as in foo below), dill.source.importable(bar) will puke out the entire history file. So that's not good. The following code reproduces the error.

>>> def foo(f):
...   squared = lambda x: f(x)**2
...   return squared
... 
>>> @foo
... def bar(x):
...   return 2*x
>>> 
>>> print dill.source.importable(bar)

[mmckerns]

fixed, I think, in e78cd06