slack-term: init at 0.4.1

By default all warnings were printed. This occasionally resulted in
a lot of warnings leading to builds being killed.

This commit reduces the amount of warnings printed.

… to fix eval

This reverts commit 3fc7d5e, reversing
changes made to 1fddf2b.

The idea is good, however, before enforcing, make sure all occurences
are fixed.

(cherry picked from commit 3dc0838)
Forward-picking from staging-next.  The CVE is marked as critical,
and the amount of rebuilds isn't that high (~500 linux, ~100 darwin).

This reverts commit d1de23b.
The changes turned out to be too intrusive, so we'll patch instead.
Discussion: NixOS/systemd#24

There are some security fixes among those.