CPAN Testers error message: Unknown open() mode '<&' at t/03_input_processing.t line 46.

Specifically, line 46 refers to:

    open STDIN, '<&', $fh
        or do { warn "set STDIN = \$fh=\\$fh: $!"; return undef; };
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(I find it strange that it flagged on line 46, because line 42 has similar code

    open my $oldin, "<&STDIN"
        or do { warn "dup STDIN to \$fh=\\$fh: $!"; return undef; };
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...which seems to be using the same feature. So why did it flag on 46, but not 42?)

(full source: https://metacpan.org/source/PETERCJ/Games-Literati-0.04/t/03_input_processing.t)

perlver output:

C:>perlver t\03_input_processing.t

       ------------------------------------------------------
     | file                    | explicit | syntax | external |
     | ------------------------------------------------------ |
     | t\03_input_processing.t | v5.6.0   | v5.6.0 | n/a      |
     | ------------------------------------------------------ |
     | Minimum explicit version : v5.6.0                        |
     | Minimum syntax version   : v5.6.0                        |
     | Minimum version of perl  : v5.6.0                        |
       ------------------------------------------------------
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Before I send a bug report to Perl::MinimumVersion for not catching that apparent incompatibility with 5.6.2, I did some more searching, and found open() with more than two arguments. Reading that, it seems to indicate that 5.6.1 was the first to include 3-argument open(). Did I read that correctly? If so, am I correct in concluding that's a separate bug in perlver()? ie, that it should have flagged 3-argument open as requiring 5.6.1?

I couldn't find the perldelta that indicated when '<&' open mode was introduced. I tried looking specifically for an archive of the Perl 5.6 perldocs, but my google-foo isn't that good, apparently. And I don't have access to Perl 5.6.* to look at the docs directly. (I'm mostly on Windows, and Strawberry Perl doesn't go back that far, and ActivePerl only allows older versions for Business or Enterprise Editions. I have access to a machine at $work that has 5.8.5, which is how I know it works by then. But while doing a quick run of a perl script during my coffee break is forgivable, installing a whole old version of perl on that server, even if I did a local installation, would be highly frowned upon, and I enjoy my $paycheck.) So is there a Monk who knows or can easily point me to when '<&' was introduced? I'd like to have 'proof' to supply during my '<&' bug report, but cannot find it, aside from my anecdotal evidence from the CPAN Testers 5.6.2 failure.

Also, more importantly, how do I solve this problem in my test suite? For now, the redirection is only used because the function it's testing gets its input from STDIN, and for the test suite, I wanted to provide input to that function to test it :-). But the redirection isn't used in the module itself, so it's 5.6-compatible. Should I figure out a workaround for the test suite? If so, I desire recommendations from my fellow Monks as to a 5.6-compatible method of testing that function. Or should I just plan skip_all => "Cannot redirect STDIN in perl $]" if $] lt '5.008';?

(Historical note: I'm reluctant to claim that the module requires something higher than 5.6, when it's just the test suite that requires it. That seems rude, especially since the original module that I inherited apparently worked under 5.6, and nothing I've done to improve the module should change that. Why be rude to a Scrabble/Literati player from the early 2000s who doesn't feel the need to upgrade perl just to optimize points, who wants bug fixes and/or to include Words with Friends scoring now?)

Finally, is there any easy way to get a copy of 5.6.0 for Windows? Or is there a small, easy to install linux virtual machine that has 5.6.0 pre-installed?

UPDATE: fix typos

UPDATE: add <readmore>