Message 292799 - Python tracker
Python 2.7 allows indexing an Exception object to access its args list.
>>> e=Exception('foo','bar','baz')
>>> assert e[0] is e.args[0]
This doesn't work in 3.5:
>>> e=Exception('foo','bar','baz')
>>> e.args[0]
'foo'
>>> e[0]
TypeError: 'Exception' object is not subscriptable
This conversion (e[x] -> e.args[x]) seems like it ought to be fairly straightforward to support in 2to3.