pip install script warnings should ignore dirname(sys.executable) #5157
Description
From #4553 (comment)
this is a common use case this PR did not cover.
if the executable is installed in dirname(sys.executable), we can skip the warning. Basically, treat dirname(sys.executable) as being a directory on PATH.
The "use case" above, is of installation using venv/bin/pip when invoking without activating a virtualenv.
@pfmoore doesn't feel strongly either way. @ncoghlan is in favour.