updated for version 7.3.501

Problem:    Error for "flush" not being defined when using Ruby command.
Solution:   Defined "flush" as a no-op method. (Kent Sibilev)

src/version.c

@@ -714,6 +714,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    501,
 /**/
     500,
 /**/