Several days ago I had a question about removing index.php from the address bar, so the address of the page looks shorter and better. The shortest solution of this problem w
You could try using [L,R=307] instead. 307's must not change the request-method according to the spec, but I don't know how browser implemented 307.
[L,R=307]
But the root of the problem is the use of
Just leave the action empty to POST to the current url e.g.