updated for version 7.3.917
Problem:    When a path ends in a backslash appending a comma has the wrong
            effect.
Solution:   Replace a trailing backslash with a slash. (Nazri Ramliy)
diff --git a/src/misc1.c b/src/misc1.c
index 96d268d..789aad3 100644
--- a/src/misc1.c
+++ b/src/misc1.c
@@ -10135,6 +10135,15 @@
 
 	if (ga_grow(gap, 1) == FAIL)
 	    break;
+
+# if defined(MSWIN) || defined(MSDOS)
+	/* Avoid the path ending in a backslash, it fails when a comma is
+	 * appended. */
+	len = STRLEN(buf);
+	if (buf[len - 1] == '\\')
+	    buf[len - 1] = '/';
+# endif
+
 	p = vim_strsave(buf);
 	if (p == NULL)
 	    break;