:py3 command does not work in macvim launching from dock

Describe the bug
:py3 command works correctly in mvim which launches from terminal, but does not work in mvim launching from dock.

To Reproduce
Detailed steps to reproduce the behavior:

1. launch macvim from dock
2. :py3 import subprocess
3. :py3 print( subprocess.Popen('rg ""', shell=True, stdout=subprocess.PIPE).stdout.read() )
4. show nothing

Expected behavior

1. launch macvim from terminal
2. :py3 import subprocess
3. :py3 print( subprocess.Popen('rg ""', shell=True, stdout=subprocess.PIPE).stdout.read() )
4. show the rg output lines

Screenshots
The wrong one:

The correct one:

Environment (please complete the following information):
Vim version:

• OS: [e.g. Ubuntu 18.04, Windows 10 1809, macOS 10.14]
  

Additional context
I installed macvim by brew cask install macvim

Inizia confrontando l’ambiente disponibile per le chiamate :py3 subprocess quando MacVim viene avviato dal Dock rispetto a quando viene avviato da un terminale, usando il comando rg riportato come riproduttore. Conferma il completamento quando l’app avviata dal Dock produce lo stesso output di rg dell’app avviata dal terminale.