This check was only occurring in one branch of the conditional.
As a result, if you ran `brew upgrade` with no args and there were no packages to upgrade,
the nonsensical message
"==> Upgrading 0 outdated package, with result:"
would be printed.
ClosesHomebrew/homebrew#21316.
Signed-off-by: Jack Nagel <jacknagel@gmail.com>