From 957aa9f977a9c01c6330e45c0ed1b921ac7de0c0 Mon Sep 17 00:00:00 2001
From: Vitor Santos Costa <vsc@dcc.fc.up.pt>
Date: Mon, 1 Aug 2016 13:20:00 -0500
Subject: [PATCH] fix existing-stream ase for with_output_to/2

---
 os/format.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/os/format.c b/os/format.c
index fd1003976..cb8f68b8d 100644
--- a/os/format.c
+++ b/os/format.c
@@ -1210,10 +1210,11 @@ static Int with_output_to(USES_REGS1) {
       (f == FunctorAtom || f == FunctorString || f == FunctorCodes1 ||
        f == FunctorCodes || f == FunctorChars1 || f == FunctorChars)) {
     output_stream = Yap_OpenBufWriteStream(PASS_REGS1);
-    mem_stream = true;
+    my_mem_stream = true;
   } else {
     /* needs to change LOCAL_c_output_stream for write */
     output_stream = Yap_CheckStream(ARG1, Output_Stream_f, "format/3");
+    my_mem_stream = false;
   }
   if (output_stream == -1) {
     return false;