From 90d456d2972a4b77637eeba4cce4f2697efb3a32 Mon Sep 17 00:00:00 2001
From: Karl Heuer <kwzh@gnu.org>
Date: Fri, 26 Mar 1999 17:55:42 +0000
Subject: [PATCH] (Fset_buffer_modified_p): Don't lock or unlock if
 buffer-file-name is nil.

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

diff --git a/src/buffer.c b/src/buffer.c
index e2aa5818ff1..1089872ebe7 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -807,7 +807,8 @@ A non-nil FLAG means mark the buffer modified.")
      If buffer becoming unmodified, unlock the file.  */
 
   fn = current_buffer->file_truename;
-  if (!NILP (fn))
+  /* Test buffer-file-name so that binding it to nil is effective.  */
+  if (!NILP (fn) && ! NILP (current_buffer->filename))
     {
       already = SAVE_MODIFF < MODIFF;
       if (!already && !NILP (flag))
-- 
2.39.2