Retry code throws "TypeError: 'Retrying' object is not iterable"

[Liam Young]

Since 2f49ae75 the retry code is broken as the old version of tenacity does not support using tenacity.Retrying as an iterator

To reproduce it:

$ virtualenv /tmp/layer-snap-test
$ source /tmp/layer-snap-test/bin/activate
$ pip install 'tenacity<5.0.4'
$ ./test.py
Traceback (most recent call last):
  File "./test.py", line 5, in <module>
    for attempt in tenacity.Retrying():
TypeError: 'Retrying' object is not iterable

$ cat ./test.py
#!/usr/bin/env python

import tenacity

for attempt in tenacity.Retrying():
    with attempt:
        print("Hi!")

$ pip uninstall tenacity
Found existing installation: tenacity 5.0.3
Uninstalling tenacity-5.0.3:
  Would remove:
    /tmp/layer-snap-test/lib/python3.8/site-packages/tenacity-5.0.3.dist-info/*
    /tmp/layer-snap-test/lib/python3.8/site-packages/tenacity/*
Proceed (y/n)? y
  Successfully uninstalled tenacity-5.0.3

$ pip install tenacity
Collecting tenacity
  Using cached tenacity-7.0.0-py2.py3-none-any.whl (23 kB)
Requirement already satisfied: six>=1.9.0 in ./layer-snap-test/lib/python3.8/site-packages (from tenacity) (1.16.0)
Installing collected packages: tenacity
Successfully installed tenacity-7.0.0

$ ./test.py
Hi!

[Liam Young (gnuoy)]

$ git diff 2f49ae75^ 2f49ae75
diff --git a/wheelhouse.txt b/wheelhouse.txt
index 48f8e12..f9bf12c 100644
--- a/wheelhouse.txt
+++ b/wheelhouse.txt
@@ -1 +1,4 @@
-tenacity
+# Newer versions of tenacity rely on `typing` which is in stdlib in
+# python3.5 but not python3.4. We want to continue to support
+# python3.4 (Trusty)
+tenacity<5.0.4

[Liam Young (gnuoy)]

https://code.launchpad.net/~gnuoy/layer-snap/+git/layer-snap/+merge/405019

[Aurelien Lourot (aurelien-lourot)]

Visible for example in this charm gate:
https://review.opendev.org/c/openstack/charm-octavia-diskimage-retrofit/+/798310
https://openstack-ci-reports.ubuntu.com/artifacts/8a5/798310/1/check/bionic-ussuri/8a549e7/index.html