The attached file implements a custom dict-like class (MyDict) as a minimal example of code I am using in a larger codebase. 
Before you ask, why I reimplemented a dict-like object: The real code base employs a hierarchical dict, referencing recursively to the parent dict, if a key cannot be found in the current dict.

The main code of the file defines two entries/variables for this dict:
symbols = MyDict()
symbols['abc'] = '[1, 2, 3]'
symbols['xyz'] = 'abc + abc'

and eval_text('xyz', symbols) should evaluate to the python expression as you would have evaluated those variables in a python interpreter.
While this works for the first given expression (above), it fails for this one:
symbols['xyz'] = '[abc[i]*abc[i] for i in [0, 1, 2]]'

raising NameError: name 'abc' is not defined.
The same code works perfectly in python 2.7. Hence, I assume this is a bug in python3.