The phrase "Any modification to the software submitted to the authors may be incorporated into the software under the terms of this license." could be worded better. I think Apache nails this, "Unless You explicitly state otherwise, any Contribution intentionally submitted for inclusion in the Work by You to the Licensor shall be under the terms and conditions of this License, without any additional terms or conditions". This gives some wiggle room for submissions under different license, if they are explicitly called out.
Maybe something like "Any modification to the software submitted to the authors may be incorporated into the software under the terms of this license unless explicitly stated otherwise." But I am not a lawyer, so my language might not precise enough for the situation.
From my HackerNews comment.
The phrase "Any modification to the software submitted to the authors may be incorporated into the software under the terms of this license." could be worded better. I think Apache nails this, "Unless You explicitly state otherwise, any Contribution intentionally submitted for inclusion in the Work by You to the Licensor shall be under the terms and conditions of this License, without any additional terms or conditions". This gives some wiggle room for submissions under different license, if they are explicitly called out.
Maybe something like "Any modification to the software submitted to the authors may be incorporated into the software under the terms of this license unless explicitly stated otherwise." But I am not a lawyer, so my language might not precise enough for the situation.