Give py2 support a brief stay of execution

As requested by @reaperhulk on IRC

Author: njsmith

.github/workflows/ci.yml

@@ -10,10 +10,12 @@ jobs:
       matrix:
         PYTHON:
           # Base builds
+          - {VERSION: "2.7", TOXENV: "py27"}
           - {VERSION: "3.6", TOXENV: "py36"}
           - {VERSION: "3.7", TOXENV: "py37"}
           - {VERSION: "3.8", TOXENV: "py38"}
           - {VERSION: "3.9", TOXENV: "py39"}
+          - {VERSION: "pypy2", TOXENV: "pypy"}
           - {VERSION: "pypy3", TOXENV: "pypy3"}
           # -cryptographyMain
           - {VERSION: "3.6", TOXENV: "py36-cryptographyMain"}
@@ -22,12 +24,15 @@ jobs:
           - {VERSION: "3.9", TOXENV: "py39-cryptographyMain"}
           - {VERSION: "pypy3", TOXENV: "pypy3-cryptographyMain"}
           # -cryptographyMinimum
+          - {VERSION: "2.7", TOXENV: "py27-cryptographyMinimum"}
           - {VERSION: "3.6", TOXENV: "py36-cryptographyMinimum"}
           - {VERSION: "3.7", TOXENV: "py37-cryptographyMinimum"}
           - {VERSION: "3.8", TOXENV: "py38-cryptographyMinimum"}
           - {VERSION: "3.9", TOXENV: "py39-cryptographyMinimum"}
+          - {VERSION: "pypy2", TOXENV: "pypy-cryptographyMinimum"}
           - {VERSION: "pypy3", TOXENV: "pypy3-cryptographyMinimum"}
           # Random order
+          - {VERSION: "2.7", TOXENV: "py27-randomorder"}
           - {VERSION: "3.9", TOXENV: "py39-randomorder"}
           # Downstreams
           - {VERSION: "3.7", TOXENV: "py37-twistedTrunk"}

tox.ini

@@ -1,5 +1,5 @@
 [tox]
-envlist = {pypy3,py36,py37,py38,py39}{,-cryptographyMain,-cryptographyMinimum}{,-randomorder},py37-twistedTrunk,pypi-readme,check-manifest,flake8,docs,coverage-report
+envlist = {pypy,pypy3,py27,py36,py37,py38,py39}{,-cryptographyMain,-cryptographyMinimum}{,-randomorder},py37-twistedTrunk,pypi-readme,check-manifest,flake8,docs,coverage-report
 
 [testenv]
 whitelist_externals =