Merge lp:~cjwatson/storm/py27-py35-workarounds into lp:storm

[Colin Watson]

Fix py27 and py35 tox environments.

Keeping Python 2.7 and 3.5 tests working now that they're unsupported upstream and various core packages such as pip have dropped support for them is getting harder, but it's still viable with a few hacks. Storm still needs to support these versions for now.

[Ioana Lasc (ilasc)]

review: Approve

=== modified file 'setup.py'
--- setup.py	2020-05-26 15:55:53 +0000
+++ setup.py	2021-04-06 09:12:19 +0000
@@ -28,11 +28,13 @@
     "pgbouncer >= 0.0.7",
     "postgresfixture",
     "psycopg2 >= 2.3.0",
+    "setuptools < 45; python_version < '3'",
     "testresources >= 0.2.4",
     "testtools >= 0.9.8",
     "timeline >= 0.0.2",
     "transaction >= 1.0.0",
-    "twisted >= 10.0.0",
+    "Twisted >= 10.0.0",
+    "Twisted < 21.2.0; python_version < '3'",
     "zope.component >= 3.8.0",
     "zope.configuration",
     "zope.interface >= 4.0.0",
 
=== modified file 'tox.ini'
--- tox.ini	2020-05-26 10:28:24 +0000
+++ tox.ini	2021-04-06 09:12:19 +0000
@@ -8,18 +8,22 @@
     docs
 
 [testenv]
+download =
+    py27,py35: true
 deps =
     .[test]
 passenv = STORM_TEST_RUNNER USER
 setenv =
     cextensions: STORM_CEXTENSIONS = 1
     nocextensions: STORM_CEXTENSIONS = 0
+    py27,py35: VIRTUALENV_DOWNLOAD = 1
+    py27,py35: VIRTUALENV_PIP = 20.3.4
 commands =
     python dev/test {posargs}
 
 [testenv:docs]
 basepython =
-    python3
+    python3.8
 commands =
     sphinx-build -b html -d storm/docs/_build/doctrees storm/docs storm/docs/_build/html
 deps =