Cover SEGV in utf8-c8 proc read

Covers R#2158 rakudo/rakudo#2158

S32-encoding/decoder.t

@@ -1,6 +1,6 @@
 use Test;
-
-plan 1;
+use lib $?FILE.IO.parent(2).add: 'packages'; use Test::Util;
+plan 2;
 
 
 # https://github.com/rakudo/rakudo/issues/2158
@@ -16,5 +16,21 @@ plan 1;
     ok $decoder.consume-all-chars().chars == $str.chars
         && $decoder.bytes-available == 0,
         'utf8-c8 decoder processes all bytes of all buffers';
+
+    # cover SEGV from the same Issue
+    my $content := Blob[uint8].new:
+      60,47,116,105,116,108,101,62,60,115,99,114,105,112,116,32,
+      110,111,110,99,101,61,34,99,87,116,51,68,79,109,89,119,120,79,57,75,97,
+      121,100,83,57,112,102,80,65,61,61,34,62,40,102,117,110,99,116,105,111,
+      110,40,41,123,119,105,110,100,111,119,46,103,111,111,103,108,101,61,
+      123,107,69,73,58,39,110,69,57,113,87,56,105,122,66,101,95,77,53,103,
+      76,106,108,97,68,81,68,103,39,44,107,69,88,80,73,58,39,48,44,49,51,
+      53,51,55,52,54,44,53,56,44,49,57,53,55,44,49,48,49,56;
+
+    my $temp-file := make-temp-file :$content;
+    my $prog := $*DISTRO.is-win ?? 'type' !! 'cat';
+    #?rakudo skip 'SEGV R#2158'
+    ok (run $prog, $temp-file, :enc<utf8-c8>, :out).out.slurp.chars,
+        'no SEGV when using utf8-c8 in Proc';
 }
 # vim: ft=perl6 expandtab sw=4