Log message:
extend PYTHON_VERSIONS_ for Python 3.7

Log message:
devel/py-flufl.lock: Update to 3.2.

3.2 (2017-09-03)
- Expose the host name used in the .details property, as a property.

3.1 (2017-07-15)
- Expose the SEP as a public attribute.

3.0 (2017-05-31)
- Drop Python 2.7, add Python 3.6.
- Added Windows support.
- Switch to the Apache License Version 2.0.
- Use flufl.testing for nose2 and flake8 plugins.
- Allow the claim file separator to be configurable, to support file
  systems where the vertical bar is problematic. Defaults to ^ on
  Windows and | everywhere else (unchanged).

Log message:
Import flufl.lock 2.4.1 as devel/py-flufl.lock.

The `flufl.lock` library provides an NFS-safe file-based locking
algorithm influenced by the GNU/Linux `open(2)` manpage, under
the description of the `O_EXCL` option.