Pyenv choose virtualenv directory
Short answer:  You can’t, as far as I know.
It wouldn’t really work either, right?  If you use pyenv virtualenv to install a virtualenv into a repo, and you clone that repo to another machine… how would pyenv on the new machine know to take control of the virtualenv in the repository?
Also, “you probably shouldn’t do that”.  Virtualenvs are not 100% decoupled from the underlying Python installation, and aren’t really all that portable.  And do you really want to litter your repositories with a bunch of easily replicated junk?  The “right” way to go about things is probably to to maintain a requirements.txt for pip — that way you can easily reproduce your development environment wherever you clone your repo.
That all said, there’s nothing stopping you from using plain old virtualenv to create a virtualenv anywhere you like, even if you installed virtualenv into a Python interpreter under pyenv control.  That virtualenv itself will of course not be administered by pyenv, but you can still use it as you always did…
I just began to use pyenv to manage my python versions, and began to use the pyenv virtualenv plugin to manage my virtualenvs, and so far, I have loved it. One thing I miss however, is that with virtualenv, you could actually place virtual environments in repository directories so that your repository was a completely reproducible environment. Does anyone know of a way to choose the directory of your virtualenv in pyenv?