inlineCallbacks test fails with contextvars backport installed

[twisted-trac]

	@altendky reported
Trac ID	trac#9826
Type	defect
Created	2020-05-12 15:24:54Z

[FAIL]
Traceback (most recent call last):
  File "/home/altendky/repos/twisted2/build/py36-alldeps-withcov-posix/lib/python3.6/site-packages/twisted/internet/test/test_inlinecb.py", line 124, in test_returnValueNonLocalDeferred
    self.assertMistakenMethodWarning(results)
  File "/home/altendky/repos/twisted2/build/py36-alldeps-withcov-posix/lib/python3.6/site-packages/twisted/internet/test/test_inlinecb.py", line 86, in assertMistakenMethodWarning
    "returnValue() in 'mistakenMethod' causing 'inline' to exit: "
  File "/home/altendky/repos/twisted2/build/py36-alldeps-withcov-posix/lib/python3.6/site-packages/twisted/trial/_synctest.py", line 437, in assertEqual
    super(_Assertions, self).assertEqual(first, second, msg)
  File "/home/altendky/.pyenv/versions/3.6.10/lib/python3.6/unittest/case.py", line 829, in assertEqual
    assertion_func(first, second, msg=msg)
  File "/home/altendky/.pyenv/versions/3.6.10/lib/python3.6/unittest/case.py", line 1203, in assertMultiLineEqual
    self.fail(self._formatMessage(msg, standardMsg))
twisted.trial.unittest.FailTest: "retu[34 chars]ing 'run' to exit: returnValue should only be [47 chars]acks" != "retu[34 chars]ing 'inline' to exit: returnValue should only [50 chars]acks"
- returnValue() in 'mistakenMethod' causing 'run' to exit: returnValue should only be invoked by functions decorated with inlineCallbacks
?                                            ^^
+ returnValue() in 'mistakenMethod' causing 'inline' to exit: returnValue should only be invoked by functions decorated with inlineCallbacks
?                                            ^ ++++


twisted.internet.test.test_inlinecb.NonLocalExitTests.test_returnValueNonLocalDeferred

Noticed while working on #9815 including adding a non-platform extra for sniffio which depends on the contextvars backport. Maybe this should be an enhancement but I'll mark it defect for now since the news fragment at least 'claimed support for' the contextvars backport.

Searchable metadata

trac-id__9826 9826
type__defect defect
reporter__altendky altendky
priority__normal normal
milestone__None None
branch__ 
branch_author__ 
status__closed closed
resolution__fixed fixed
component__core core
keywords__None None
time__1589297094583959 1589297094583959
changetime__1589613039783397 1589613039783397
version__None None
owner__hawkowl hawkowl
cc__altendky

[twisted-trac]

	@altendky commented

PR: #1270

[twisted-trac]

	@hawkowl set owner to @hawkowl

LGTM!

[twisted-trac]

	@altendky set status to closed

In changeset 9646db4

#!CommitTicketReference repository="" revision="9646db406454def1d5d5ce0ac89e01941450567f"
Merge altendky:9826-altendky-contextvars_backport_compatibility: Fix contextvars backport compatibility 

Author: altendky
Reviewer: hawkowl
Fixes: ticket:9826