Log Message:
py-execnet: updated to 1.8.0

1.8.0

* Dropped support for Python 3.4.

* Fixed internal leak that should make
  ``execnet`` execute remote code in the main thread more often; previously it \ 
would sometimes
  spawn a thread to execute a ``remote_exec`` call, even when the caller
  didn't issue multiple ``remote_exec`` calls at the same time. Some frameworks \ 
require code
  to execute in the main thread, so the previous behavior would break them on \ 
occasion.

* Current working directory is now
  restored when calling ``script/socketserver.py``. The script now also loops by \ 
default
  when called from the command-line.