See this execution trace:

MacBook-Pro:docs ckd$ tox
coala create: /Users/ckd/git-reps/docs/.tox/coala
coala installdeps: coala==0.11, coala-bears==0.11, requests<2.16, nodeenv
coala installed: alabaster==0.7.10,ansicolor==0.2.4,appdirs==1.4.3,astroid==1.5.3,autoflake==0.6.6,autopep8==1.3.2,Babel==2.4.0,bandit==1.4.0,chardet==3.0.4,click==6.6,cmakelint==1.3.4.1,coala==0.11.0,coala-bears==0.11.0,coala-utils==0.6.2,colorama==0.3.9,colorlog==2.10.0,cppclean==0.12,cpplint==1.3.0,decorator==4.0.11,dennis==0.9,dependency-management==0.4.0,docopt==0.6.2,docutils==0.13.1,eradicate==0.1.6,future==0.16.0,gitdb2==2.0.2,GitPython==2.1.5,guess-language-spirit==0.5.3,html-linter==0.3.0,imagesize==0.7.1,ipython-genutils==0.2.0,isort==4.2.15,Jinja2==2.9.6,jsonschema==2.6.0,jupyter-core==4.3.0,lazy-object-proxy==1.3.1,libclang-py3==3.4.0,mando==0.3.3,MarkupSafe==1.0,mccabe==0.6.1,munkres3==1.0.5.5,mypy-lang==0.4.6,nbformat==4.3.0,nltk==3.2.4,nodeenv==1.1.3,packaging==16.8,pbr==3.1.1,polib==1.0.8,proselint==0.7.0,pycodestyle==2.3.1,pydocstyle==1.1.1,pyflakes==1.4.0,Pygments==2.2.0,pylint==1.7.2,pyparsing==2.2.0,PyPrint==0.2.6,pyroma==2.2,pytz==2017.2,PyYAML==3.12,radon==1.4.0,requests==2.15.1,restructuredtext-lint==1.0.1,rstcheck==2.2,safety==0.5.1,sarge==0.1.4,scspell3k==2.1,six==1.10.0,smmap2==2.0.3,snowballstemmer==1.2.1,Sphinx==1.4.9,stevedore==1.23.0,template-remover==0.1.9,termcolor==1.1.0,traitlets==4.3.2,unidiff==0.5.4,vim-vint==0.3.13,vulture==0.10,wrapt==1.10.10,yamllint==1.6.1,yapf==0.14.0
coala runtests: PYTHONHASHSEED='2918599315'
coala runtests: commands[0] | nodeenv -p

• Install prebuilt node (8.1.3) ....Traceback (most recent call last):
  File "/Users/ckd/git-reps/docs/.tox/coala/bin/nodeenv", line 11, in <module>
  sys.exit(main())
  File "/Users/ckd/git-reps/docs/.tox/coala/lib/python3.6/site-packages/nodeenv.py", line 1022, in main
  create_environment(env_dir, opt)
  File "/Users/ckd/git-reps/docs/.tox/coala/lib/python3.6/site-packages/nodeenv.py", line 855, in create_environment
  install_node(env_dir, src_dir, opt)
  File "/Users/ckd/git-reps/docs/.tox/coala/lib/python3.6/site-packages/nodeenv.py", line 675, in install_node
  copy_node_from_prebuilt(env_dir, src_dir, opt.node)
  File "/Users/ckd/git-reps/docs/.tox/coala/lib/python3.6/site-packages/nodeenv.py", line 587, in copy_node_from_prebuilt
  copytree(src_folder, env_dir)
  File "/Users/ckd/git-reps/docs/.tox/coala/lib/python3.6/site-packages/nodeenv.py", line 568, in copytree
  shutil.copytree(s, d, symlinks, ignore)
  File "/Users/ckd/git-reps/docs/.tox/coala/lib/python3.6/shutil.py", line 315, in copytree
  os.makedirs(dst)
  File "/Users/ckd/git-reps/docs/.tox/coala/bin/../lib/python3.6/os.py", line 220, in makedirs
  mkdir(name, mode)
  FileExistsError: [Errno 17] File exists: '/Users/ckd/git-reps/docs/.tox/coala/bin'
  ERROR: InvocationError: '/Users/ckd/git-reps/docs/.tox/coala/bin/nodeenv -p'