[PATCH 4/4] t0021: fix filehandle usage on older perl

The rot13-filter.pl script calls methods on implicitly defined filehandles (STDOUT, and the result of an open() call). Prior to perl 5.13, these methods are not automatically loaded, and perl will complain with:

  Can't locate object method "flush" via package "IO::Handle"

Let's explicitly load IO::File (which inherits from IO::Handle). That's more than we need for just "flush", but matches what perl has done since:

  http://perl5.git.perl.org/perl.git/commit/15e6cdd91beb4cefae4b65e855d68cf64766965d

Signed-off-by: Jeff King <peff@peff.net>
---
I see J6t solved this a week ago using "FileHandle". These days that is
basically a compatibility synonym for IO::File. I think both should be
available pretty much everywhere, so I went with IO::File for the
reasons above. But if that doesn't work for some reason, switching to
"use FileHandle" should be OK, too.

I don't have an old enough perl easily available to test it either way.

 t/t0021/rot13-filter.pl | 1 +
 1 file changed, 1 insertion(+)