Rip out more Python 2 stuff.

Makefile

@@ -17,7 +17,7 @@ PYTHON=python
 export PYTHON
 PYFLAKES=flake8
 export PYFLAKES
-VIRTUAL_ENV=./.tox/py27
+VIRTUAL_ENV=./.tox/py37
 SOURCES=src/allmydata static misc setup.py
 APPNAME=tahoe-lafs
 TEST_SUITE=allmydata
@@ -33,9 +33,9 @@ default:
 ## Run all tests and code reports
 test: .tox/create-venvs.log
 # Run codechecks first since it takes the least time to report issues early.
-	tox --develop -e codechecks
+	tox --develop -e codechecks3
 # Run all the test environments in parallel to reduce run-time
-	tox --develop -p auto -e 'py27,py37,pypy27'
+	tox --develop -p auto -e 'py37'
 .PHONY: test-venv-coverage
 ## Run all tests with coverage collection and reporting.
 test-venv-coverage:
@@ -136,7 +136,7 @@ count-lines:
 # Here is a list of testing tools that can be run with 'python' from a
 # virtualenv in which Tahoe has been installed. There used to be Makefile
 # targets for each, but the exact path to a suitable python is now up to the
-# developer. But as a hint, after running 'tox', ./.tox/py27/bin/python will
+# developer. But as a hint, after running 'tox', ./.tox/py37/bin/python will
 # probably work.
 
 # src/allmydata/test/bench_dirnode.py

docs/release-checklist.rst

@@ -122,7 +122,7 @@ they will need to evaluate which contributors' signatures they trust.
 
   - these should all pass:
 
-    - tox -e py27,codechecks,docs,integration
+    - tox -e py37,codechecks3,docs,integration
 
   - these can fail (ideally they should not of course):
 

tox.ini

@@ -7,7 +7,6 @@
 # the tox-gh-actions package.
 [gh-actions]
 python =
-    2.7: py27-coverage,codechecks
     3.7: py37-coverage,typechecks,codechecks3
     3.8: py38-coverage
     3.9: py39-coverage
@@ -17,7 +16,7 @@ python =
 twisted = 1
 
 [tox]
-envlist = typechecks,codechecks,codechecks3,py{27,37,38,39}-{coverage},pypy27,pypy3,integration,integration3
+envlist = typechecks,codechecks3,py{37,38,39}-{coverage},pypy27,pypy3,integration,integration3
 minversion = 2.4
 
 [testenv]
@@ -110,18 +109,6 @@ commands =
          coverage report
 
 
-# Once 2.7 is dropped, this can be removed. It just does flake8 with Python 2
-# since that can give different results than flake8 on Python 3.
-[testenv:codechecks]
-basepython = python2.7
-setenv =
-	 # If no positional arguments are given, try to run the checks on the
-	 # entire codebase, including various pieces of supporting code.
-	 DEFAULT_FILES=src integration static misc setup.py
-commands =
-         flake8 {posargs:{env:DEFAULT_FILES}}
-
-
 [testenv:codechecks3]
 basepython = python3
 deps =