updated for version 7.4.684
Problem:    When starting several Vim instances in diff mode, the temp files
            used may not be unique. (Issue 353)
Solution:   Add an argument to vim_tempname() to keep the file.
diff --git a/src/spell.c b/src/spell.c
index 31bfa95..80a7d18 100644
--- a/src/spell.c
+++ b/src/spell.c
@@ -9426,7 +9426,7 @@
     {
 	if (int_wordlist == NULL)
 	{
-	    int_wordlist = vim_tempname('s');
+	    int_wordlist = vim_tempname('s', FALSE);
 	    if (int_wordlist == NULL)
 		return;
 	}