[issue34215] streams.py:readuntil IncompleteReadError is message is incorrect

[Tyler Bell]

New submission from Tyler Bell <mrbell321 at gmail.com>:

This may have already been cleared as I opened the PR months ago
But the gist is that the Exception is misleading and the test is incorrect.

----------
components: Library (Lib)
messages: 322329
nosy: mrbell321 at gmail.com
priority: normal
pull_requests: 7975
severity: normal
status: open
title: streams.py:readuntil IncompleteReadError is message is incorrect
type: enhancement
versions: Python 3.5

_______________________________________
Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue34215>
_______________________________________