Re: [pgadmin-hackers] [pgAdmin4] [PATCH] Simplify Server's python setup

One where the virtualenv is in a path that's not related to the
location of the runtime. If I'm reading the code correctly, you're
taking the appDir (the location of the runtime executable) and
appending a platform-specific path to the virtual env (e.g. on Linux,
"/../venv/bin/"), and expecting to find the Python executable in the
resulting directory.

However, in a dev environment, we may have the venv in
~/.virtualenvs/pgadmin4 and the runtime in
~/git/pgadmin4/runtime/<builddir> for example. In an RPM based
installation, there is no virtualenv - the Python code is installed in
the system site-packages directory, and the runtime in /usr/bin (which
may or may not be where python is found - assuming it's called that,
and not python3).

> Granted, "/python" is nonsense and should probably just be "python". Also, I
> think PATH doesn't need to be touched at all anymore, so the lines involving
> pathEnv can be removed.

>
> How about a settings key to force the program name? That would allow
> choosing any other virtualenv to run with.

That might be a better option, and is basically how (for example)
Pycharms does it. In that case I'd argue that we should search
relative known locations first (such as the installers on Windows/Mac
would lay down), and then fall back to the configured Python
executable. That would allow installed copies to remain independent of
development copies. The only possible wrinkle would be whether a
relocatable installation such as the aforementioned installers would
be able to find their environments based purely on the executable
name.