pyenv

Make sure you have checked all steps below.

Please consider implementing the feature as a hook script or plugin as a first step.
- pyenv has some powerful support for plugins and hook scripts. Please refer to Authoring plugins for details and try to implement it as a plugin if possible.
Please consider contributing the patch upstream to rbenv, since we have borrowed most of the code from that project.
- We occasionally import the changes from rbenv. In general, you can expect changes made in rbenv will be imported to pyenv too, eventually.
- Generally speaking, we prefer not to make changes in the core in order to keep compatibility with rbenv.
My PR addresses the following pyenv issue (if any)
- https://github.com/pyenv/pyenv/issues/XXXX