POE::Pipe and its subclasses work best using Cygwin's pipe(), not IO:…

…:Socket.

Previous Cygwin versions work better with sockets.  If 01_sysrw.t hangs for
you, upgrade your Cygwin and its Perl.

t/10_units/04_drivers/01_sysrw.t

@@ -97,18 +97,8 @@ ok( $d->get_out_messages_buffered() == 1, "one message buffered" );
 }
 
 # Remaining tests require some live handles.
-# cygwin seems to block on syswrite() and close() even though a handle
-# is non-blocking.  Force the pipe to use Internet domain sockets.
-# This solves the syswrite() problem.  Later we call shutdown(2) on
-# the write side rather than close(), which solves that end of things.
-
-my ($r, $w);
-if ($^O eq "cygwin") {
-  ($r, $w) = POE::Pipe::OneWay->new("inet");
-}
-else {
-  ($r, $w) = POE::Pipe::OneWay->new();
-}
+
+my ($r, $w) = POE::Pipe::OneWay->new();
 die "can't open a pipe: $!" unless $r;
 
 nonblocking($w);
@@ -139,12 +129,7 @@ while (flush_remaining_buffer($d, $w)) {
 # Get() returns undef ($! == 0) on EOF.
 
 { write_until_pipe_is_full($d, $w);
-  if ($^O eq "cygwin") {
-    shutdown($w, 2);
-  }
-  else {
-    close($w);
-  }
+  close($w);
 
   open(SAVE_STDERR, ">&STDERR") or die $!;
   close(STDERR) or die $!;