title: Pyenv: How to 'rebuild' virtualenvs after rebuilding python
body: <p>I rebuilt python 3.7 to get pyinstaller to work on Mac, and it seems to have deleted all my virtualenvs using 3.7.0.</p>
  
  <p>The .python-version files still exist, and they point at the location I would expect. But when I run 'pyenv virtualenvs' there's no python3 environments at all, and in the project directory, the python command doesn't work at all.</p>
  
  <pre><code>3.7.0/envs/some-scripts```
  
  
  ```$ ls ~/.pyenv/versions/3.7.0/envs/some-scripts/bin/
  activate        chardetect      macho_find      netaddr         pydoc           pyi-makespec        python3
  activate.csh        easy_install        macho_standalone    pip         pyi-archive_viewer  pyi-set_version
  activate.fish       easy_install-3.7    mako-render     pip3            pyi-bindepend       pyinstaller
  alembic         macho_dump      natsort         pip3.7          pyi-grab_version    python```
  
  
  ```$ pyenv virtualenvs
    2.7.10/envs/some-scripts-2 (created from /Users/mememe/.pyenv/versions/2.7.10)
    2.7.10/envs/gdrive (created from /Users/mememe/.pyenv/versions/2.7.10)
    arista-scripts-2 (created from /Users/mememe/.pyenv/versions/2.7.10)
    gdrive (created from /Users/mememe/.pyenv/versions/2.7.10)```
  
  See? no 3, and no asterisk, despite being in the project directory.
  </code></pre>