tee: reduce if block

[oech3]

No description provided.

[github-actions]

GNU testsuite comparison:

Skip an intermittent issue tests/date/date-locale-hour (fails in this run but passes in the 'main' branch)
Skipping an intermittent issue tests/tty/tty-eof (passes in this run but fails in the 'main' branch)
Congrats! The gnu test tests/tail/pipe-f2 is no longer failing!
Note: The gnu test tests/tail/tail-n0f was skipped on 'main' but is now failing.

[cakebaker]

Thanks!