"#39861: Switch module doesn't like subroutine prototypes"

Recently I faced an unexpected perl5's behaviour.
This simple and valid code

#!/usr/bin/perl
use POSIX;
use strict;

use Switch;

sub foo($) {
    switch($_[0]) {
        case /ACK/i {
            return "ACK";
        }
        case /NACK/i {
            return "NACK";
        }
    }
}

1;
failed to execute due to
syntax error at ./test.pl line 8, near ") {"
syntax error at ./test.pl line 15, near "}"
Bareword "case" not allowed while "strict subs" in use at ./test.pl line 12.
Bareword "NACK" not allowed while "strict subs" in use at ./test.pl line 12.
Execution of ./test.pl aborted due to compilation errors.


If we change foo's prototype requirement to expect more than one scalar
parameters, or drop any requirements - everything will cure and work just
as expected. IOW, case with one scalar parameter is kind of special (read broken).

This turned out to be known problem (#39861, according to Perl5's bugzilla )...
Since around 2004. Only one thing remains to write  - WTF?