I have `g:python3_host_prog` set to the system Python, where a package
is also installed to provide the "neovim" module.
`:checkhealth provider` however displays a warning for this:
> Your virtualenv is not set up optimally.
This is because /usr/bin/python is not in /home/user/.pyenv.
I think this warning should not get displayed if host_prog_var exists.
It goes back to the initial commit (20447ba09), and is maybe only
missing the `!` there as with the previous commit.
Full output:
```
- INFO: pyenv: /home/user/.pyenv/libexec/pyenv
- INFO: pyenv root: /home/user/.pyenv
- INFO: Using: g:python3_host_prog = "/usr/bin/python"
- WARNING: Your virtualenv is not set up optimally (/usr/bin/python is not in /home/user/.pyenv).
- ADVICE:
- Create a virtualenv specifically for Neovim and use `g:python3_host_prog`. This will avoid the need to install Neovim's Python module in each virtualenv.
- WARNING: $VIRTUAL_ENV exists but appears to be inactive. This could lead to unexpected results.
- ADVICE:
- If you are using Zsh, see: http://vi.stackexchange.com/a/7654
- INFO: Executable: /usr/bin/python
- INFO: Python3 version: 3.6.4
- INFO: python-neovim version: 0.2.1
- OK: Latest python-neovim is installed: 0.2.1
```