(Fkill_buffer): When killing indirect buffer,

unchain that buffer's markers (only) from the common chain.
Don't rekill this buffer's indirect buffers that are dead.
Do nothing if this buffer is already dead.

src/buffer.c

@@ -889,6 +889,10 @@ with `delete-process'.")
 
   b = XBUFFER (buf);
 
+  /* Avoid trouble for buffer already dead.  */
+  if (NILP (b->name))
+    return Qnil;
+
   /* Query if the buffer is still modified.  */
   if (INTERACTIVE && !NILP (b->filename)
       && BUF_MODIFF (b) > BUF_SAVE_MODIFF (b))
@@ -946,7 +950,9 @@ with `delete-process'.")
       GCPRO1 (buf);
 
       for (other = all_buffers; other; other = other->next)
-	if (other->base_buffer == b)
+	/* all_buffers contains dead buffers too;
+	   don't re-kill them.  */
+	if (other->base_buffer == b && !NILP (other->name))
 	  {
 	    Lisp_Object buf;
 	    XSETBUFFER (buf, other);
@@ -992,11 +998,26 @@ with `delete-process'.")
 	internal_delete_file (b->auto_save_file_name);
     }
 
-  if (! b->base_buffer)
+  if (b->base_buffer)
+    {
+      /* Unchain all markers that belong to this indirect buffer.
+	 Don't unchain the markers that belong to the base buffer
+	 or its other indirect buffers.  */
+      for (tem = BUF_MARKERS (b); !NILP (tem); )
+	{
+	  Lisp_Object next;
+	  m = XMARKER (tem);
+	  next = m->chain;
+	  if (m->buffer == b)
+	    unchain_marker (tem);
+	  tem = next;
+	}
+    }
+  else
     {
-      /* Unchain all markers of this buffer
+      /* Unchain all markers of this buffer and its indirect buffers.
 	 and leave them pointing nowhere.  */
-      for (tem = BUF_MARKERS (b); !EQ (tem, Qnil); )
+      for (tem = BUF_MARKERS (b); !NILP (tem); )
 	{
 	  m = XMARKER (tem);
 	  m->buffer = 0;