Merge branch 'feature/build-cleanup' into 'master'

Feature/build cleanup

See merge request python-devs/importlib_metadata!110

Author: jaraco

tox.ini

@@ -1,14 +1,13 @@
 [tox]
 envlist = {py27,py35,py36,py37,py38}{,-cov,-diffcov},qa,docs,perf
 skip_missing_interpreters = True
-
+minversion = 3.2
+# Ensure that a late version of pip is used even on tox-venv.
+requires =
+    tox-pip-version>=0.0.6
 
 [testenv]
-# Pin pip at version less than 19.1, see https://gitlab.com/python-devs/importlib_metadata/issues/54 for background
-# Full discussion at https://discuss.python.org/t/pip-19-1-and-installing-in-editable-mode-with-pyproject-toml/1553
-# One liner copied from https://github.com/ansible/molecule/pull/2009/files
-install_command =
-    python -c 'import subprocess, sys; pip_inst_cmd = sys.executable, "-m", "pip", "install"; subprocess.check_call(pip_inst_cmd + ("pip<19.1", )); subprocess.check_call(pip_inst_cmd + tuple(sys.argv[1:]))' {opts} {packages}
+pip_version = pip
 commands =
     !cov,!diffcov: python -m unittest discover {posargs}
     cov,diffcov: python -m coverage run {[coverage]rc} -m unittest discover {posargs}