* Fix csvfile traceback on Python3 (#37625)
* Fix csvfile traceback on Python3
The csvfile lookup uses some custom iterators. These needed to be
ported to handle the python3 iterator protocol. In addition, the
csvfile module takes an iterator of byte strings in Python2 and an
iterator of text strings in Python3
Fixes#36808
(cherry picked from commit 09325b619e)
* Add changelog entry for csvfile python3 fix
