GeezerVison

venv installs the activation scripts (activate, activate.csh,
activate.fish) by copying the packaged template's mode onto the output, so
they always end up 0644 regardless of the process umask or any default ACL on
the target directory. Every other file venv creates (the pip wrappers, and
any file written afterwards) honors the umask and ACL, so the activation scripts
are the odd ones out: on a directory with a group-writable default ACL they come
out rw-r--r-- while pip* come out rw-rw-rw-.

Activation scripts are sourced, not executed, so they need no special mode. This
drops the mode-copying in install_scripts so the scripts inherit the umask and
default ACL like everything else venv writes.

The added regression test drives the process umask, so it needs no ACL support
and runs on every POSIX platform.

• Issue: venv module not respecting ACLs #127172