clean remaining references to 2to3

.travis.yml

@@ -80,9 +80,6 @@ before_script:
 script:
   - tox -e $(echo py$TRAVIS_PYTHON_VERSION-mg$PYMONGO | tr -d . | sed -e 's/pypypy/pypy/') -- -a "--cov=mongoengine"
 
-# For now only submit coveralls for Python v2.7. Python v3.x currently shows
-# 0% coverage. That's caused by 'use_2to3', which builds the py3-compatible
-# code in a separate dir and runs tests on that.
 after_success:
 - coveralls --verbose
 

CONTRIBUTING.rst

@@ -22,10 +22,6 @@ Supported Interpreters
 
 MongoEngine supports CPython 2.7 and newer. Language
 features not supported by all interpreters can not be used.
-The codebase is written in a compatible manner for python 2 & 3 so it
-is important that this is taken into account when it comes to discrepencies
-between the 2 versions (check this https://python-future.org/compatible_idioms.html).
-Travis runs run the tests against the different versions as a safety net.
 
 Python 2/3 compatibility
 ----------------------