Documentation for subprocess.Popen()'s "user", "group", "extra_groups" args may need more usage info

[ald-extrahop]

It's very easy for someone that doesn't really understand the details of how to drop privileges (e.g. me) to use the "user", "group", and "extra_groups" args to subprocess.Popen() incorrectly ... or at least not in a way that gets the results they expect. Since there are potentially many reasonable patterns for using these It might be at least worth documenting that just setting "user" isn't a replacement for running a command under su or runuser.

Linked PRs

• gh-94632: document the subprocess need for extra_groups=() with user= #148129
• [3.14] gh-94632: document the subprocess need for extra_groups=() with user= (GH-148129) #148130
• [3.13] gh-94632: document the subprocess need for extra_groups=() with user= (GH-148129) #148131
• [3.12] gh-94632: document the subprocess need for extra_groups=() with user= (GH-148129) #148132
• [3.10] gh-94632: document the subprocess need for extra_groups=() with user= (GH-148129) #148134
• [3.11] gh-94632: document the subprocess need for extra_groups=() with user= (GH-148129) #148133