Make isort run with Python 3 only

As isort is primarily used as a command-line tool, it is in a good
position to move to Python 3 only. Other command-line-only tools have
begun moving to Python 3. For example: black, mypy, pylint, and Sphinx.
It will continue to support formatting Python 2 code, so users can still
format their Python 2 projects.

Allows for many code cleanups. By removing these workarounds, the
project will be easier to maintain and reduce testing resources.

Python 2 is scheduled to be EOL on January 1, 2020. The Python community
is moving on.

https://www.python.org/dev/peps/pep-0373/

For reasons to drop Python 2 support, see:

https://python3statement.org/

For an overview of projects that have dropped Python 2 support entirely,
see:

https://hugovk.github.io/drop-python/2.7/

Fixes #808

1 files changed, 2 insertions, 1 deletions

diff --git a/tox.ini b/tox.ini
index 0e5b1db9..cb36b189 100644
--- a/tox.ini
+++ b/tox.ini
@@ -3,7 +3,7 @@ minversion = 2.4
 envlist =
     isort-check,
     lint,
-    py{27,34,35,36,37,py,py3}
+    py{34,35,36,37,py3}
 
 [testenv]
 deps =
@@ -15,6 +15,7 @@ extras =
 commands = py.test test_isort.py {posargs}
 
 [testenv:isort-check]
+basepython = python3
 commands = python setup.py isort
 
 [testenv:lint]