Names not defined in list comprehension in the IPython shell

In the IPython shell, you can't seem to access names from within list comprehensions:

``` py
In [16]: a = 1

In [17]: [a for i in range(10)]
---------------------------------------------------------------------------
NameError Traceback (most recent call last)
/Users/aaronmeurer/Documents/Continuum/conda/conda/resolve.py in ()
----> 1 [a for i in range(10)]

/Users/aaronmeurer/Documents/Continuum/conda/conda/resolve.py in (.0)
----> 1 [a for i in range(10)]

NameError: global name 'a' is not defined
```

It doesn't matter if the name was defined within the session or if it comes from the function you are debugging. This is debugging within a function scope, if that matters.

Start by reproducing the list-comprehension failure in the IPython shell while debugging a function, using the example in the issue. Trace how the debugger evaluates expressions and resolves session or function-scope names. Done means names available in the relevant scope can be accessed from list comprehensions without the reported NameError.

Written by the indexing model from the issue text.