[vtysh] Return non-zero exit code on error.

If passed a bad command, return non-zero exit code
diff --git a/vtysh/vtysh.c b/vtysh/vtysh.c
index 20f7df4..bff0632 100644
--- a/vtysh/vtysh.c
+++ b/vtysh/vtysh.c
@@ -275,7 +275,7 @@
 static int
 vtysh_execute_func (const char *line, int pager)
 {
-  int ret, cmd_stat = CMD_SUCCESS;
+  int ret, cmd_stat;
   u_int i;
   vector vline;
   struct cmd_element *cmd;
@@ -336,6 +336,7 @@
 
   cmd_free_strvec (vline);
 
+  cmd_stat = ret;
   switch (ret)
     {
     case CMD_WARNING: