Remove dubious thread dirhandle cloning test

This tests makes assumptions that are only true for the current fchdir
based implementation of dirhandle cloning. In particular that the cloned
dirhandle is entirely separate from the original. This is not
appropriate for the upcoming fdopendir based implementation.

Author: Leont

t/op/threads-dirh.t

@@ -13,16 +13,12 @@ BEGIN {
      skip_all_if_miniperl("no dynamic loading on miniperl, no threads");
      skip_all("runs out of memory on some EBCDIC") if $ENV{PERL_SKIP_BIG_MEM_TESTS};
 
-     plan(6);
+     plan(1);
 }
 
 use strict;
 use warnings;
 use threads;
-use threads::shared;
-use File::Path;
-use File::Spec::Functions qw 'updir catdir';
-use Cwd 'getcwd';
 
 # Basic sanity check: make sure this does not crash
 fresh_perl_is <<'# this is no comment', 'ok', {}, 'crash when duping dirh';
@@ -31,101 +27,3 @@ fresh_perl_is <<'# this is no comment', 'ok', {}, 'crash when duping dirh';
    async{}->join for 1..2;
    print "ok";
 # this is no comment
-
-my $dir;
-SKIP: {
- skip "telldir or seekdir not defined on this platform", 5
-    if !$Config::Config{d_telldir} || !$Config::Config{d_seekdir};
- my $skip = sub {
-   chdir($dir);
-   chdir updir;
-   skip $_[0], 5
- };
-
- if(!$Config::Config{d_fchdir} && $^O ne "MSWin32") {
-  $::TODO = 'dir handle cloning currently requires fchdir on non-Windows platforms';
- }
-
- my @w :shared; # warnings accumulator
- local $SIG{__WARN__} = sub { push @w, $_[0] };
-
- $dir = catdir getcwd(), "thrext$$" . int rand() * 100000;
-
- rmtree($dir) if -d $dir;
- mkdir($dir);
-
- # Create a dir structure like this:
- #   $dir
- #     |
- #     `- toberead
- #            |
- #            +---- thrit
- #            |
- #            +---- rile
- #            |
- #            `---- zor
-
- chdir($dir);
- mkdir 'toberead';
- chdir 'toberead';
- {open my $fh, ">thrit" or &$skip("Cannot create file thrit")}
- {open my $fh, ">rile" or &$skip("Cannot create file rile")}
- {open my $fh, ">zor" or &$skip("Cannot create file zor")}
- chdir updir;
-
- # Then test that dir iterators are cloned correctly.
-
- opendir my $toberead, 'toberead';
- my $start_pos = telldir $toberead;
- my @first_2 = (scalar readdir $toberead, scalar readdir $toberead);
- my @from_thread = @{; async { [readdir $toberead ] } ->join };
- my @from_main = readdir $toberead;
- is join('-', sort @from_thread), join('-', sort @from_main),
-     'dir iterator is copied from one thread to another';
- like
-   join('-', "", sort(@first_2, @from_thread), ""),
-   qr/(?<!-rile)-rile-thrit-zor-(?!zor-)/i,
-  'cloned iterator iterates exactly once over everything not already seen';
-
- seekdir $toberead, $start_pos;
- readdir $toberead for 1 .. @first_2+@from_thread;
- {
-  local $::TODO; # This always passes when dir handles are not cloned.
-  is
-    async { readdir $toberead // 'undef' } ->join, 'undef',
-   'cloned dir iterator that points to the end of the directory'
-  ;
- }
-
- # Make sure the cloning code can handle file names longer than 255 chars
- SKIP: {
-  chdir 'toberead';
-  open my $fh,
-    ">floccipaucinihilopilification-"
-   . "pneumonoultramicroscopicsilicovolcanoconiosis-"
-   . "lopadotemachoselachogaleokranioleipsanodrimypotrimmatosilphiokarabo"
-   . "melitokatakechymenokichlepikossyphophattoperisteralektryonoptokephal"
-   . "liokinklopeleiolagoiosiraiobaphetraganopterygon"
-    or
-     chdir updir,
-     skip("OS does not support long file names (and I mean *long*)", 1);
-  chdir updir;
-  opendir my $dirh, "toberead";
-  my $test_name
-    = "dir iterators can be cloned when the next fn > 255 chars";
-  while() {
-   my $pos = telldir $dirh;
-   my $fn = readdir($dirh);
-   if(!defined $fn) { fail($test_name); last SKIP; }
-   if($fn =~ 'lagoio') { 
-    seekdir $dirh, $pos;
-    last;
-   }
-  }
-  is length async { scalar readdir $dirh } ->join, 258, $test_name;
- }
-
- is scalar @w, 0, 'no warnings during all that' or diag @w;
- chdir updir;
-}
-rmtree($dir);