updated for version 7.4.645
Problem:    When splitting the window in a BufAdd autocommand while still in
            the first, empty buffer the window count is wrong.
Solution:   Do not reset b_nwindows to zero and don't increment it.
diff --git a/src/ex_cmds.c b/src/ex_cmds.c
index 8492872..314a466 100644
--- a/src/ex_cmds.c
+++ b/src/ex_cmds.c
@@ -3375,7 +3375,6 @@
 	if (buf->b_ml.ml_mfp == NULL)		/* no memfile yet */
 	{
 	    oldbuf = FALSE;
-	    buf->b_nwindows = 0;
 	}
 	else					/* existing memfile */
 	{
@@ -3408,7 +3407,7 @@
 	 * Make the (new) buffer the one used by the current window.
 	 * If the old buffer becomes unused, free it if ECMD_HIDE is FALSE.
 	 * If the current buffer was empty and has no file name, curbuf
-	 * is returned by buflist_new().
+	 * is returned by buflist_new(), nothing to do here.
 	 */
 	if (buf != curbuf)
 	{
@@ -3515,8 +3514,6 @@
 	    au_new_curbuf = NULL;
 #endif
 	}
-	else
-	    ++curbuf->b_nwindows;
 
 	curwin->w_pcmark.lnum = 1;
 	curwin->w_pcmark.col = 0;