In other words, `brew install python` now complies with PEP 394[4].

  $ brew install python
  …
  ==> Caveats
  Python has been installed as
    /usr/local/bin/python3

  Unversioned symlinks `python`, `python-config`, `pip` etc. pointing to
  `python3`, `python3-config`, `pip3` etc., respectively, have been installed into
    /usr/local/opt/python/libexec/bin
  …
  $ ls -l /usr/local/bin/python{,2,3}
  lrwxr-xr-x 1 osteele staff 38 Mar 22 11:23 /usr/local/bin/python -> ../Cellar/python@2/2.7.14_3/bin/python
  lrwxr-xr-x 1 osteele staff 39 Mar 22 11:23 /usr/local/bin/python2 -> ../Cellar/python@2/2.7.14_3/bin/python2
  lrwxr-xr-x 1 osteele staff 34 Mar 31 12:27 /usr/local/bin/python3 -> ../Cellar/python/3.6.5/bin/python3

[2] https://github.com/Homebrew/homebrew-core/issues/24812

[3] https://discourse.brew.sh/t/python-and-pep-394/1813

[4] https://www.python.org/dev/peps/pep-0394/