updated for version 7.3.488
Problem:    ":help!" in a help file does not work as document.
Solution:   When in a help file don't give an error message. (thinca)
diff --git a/src/ex_cmds.c b/src/ex_cmds.c
index 661fba6..2f0f1f4 100644
--- a/src/ex_cmds.c
+++ b/src/ex_cmds.c
@@ -5546,7 +5546,7 @@
 	}
 	arg = eap->arg;
 
-	if (eap->forceit && *arg == NUL)
+	if (eap->forceit && *arg == NUL && !curbuf->b_help)
 	{
 	    EMSG(_("E478: Don't panic!"));
 	    return;