wip/portmidi: custom license or MIT?

[Manuel Kuklinski <mk%asdfghasdfgh.de@localhost>]

Hi,

as I wrote Jason privately and he kindly told me to direct / forward
this question to the mailing-list, I'm kindly asking to take a look at
the wip/portmidi license; it's unclear to me if this license, which
full version can be found here:

    https://github.com/PortMidi/portmidi/blob/master/license.txt

is either:

b) a plain MIT license

a) a custom license, which should be added to mk/license.mk

I'm asking especially because of the addition of:

- - - - - - - - - - %< - - - - - - - - - -

> /*
>  * The text above constitutes the entire PortMidi license; however, 
>  * the PortMusic community also makes the following non-binding requests:
>  *
>  * Any person wishing to distribute modifications to the Software is
>  * requested to send the modifications to the original developer so that
>  * they can be incorporated into the canonical version. It is also
>  * requested that these non-binding requests be included along with the 
>  * license above.
>  */

- - - - - - - - - - %< - - - - - - - - - -

I'm aware that this addition is just a, as stated, "non-binding request",
but I'm uncertain how to proceed with this, not only from a legal point
of view: since it's added to license.txt, does it count as a
modification of the MIT license, and shall be, as asked in question b)
stated as a custom license in mk/license.mk?

Kind regards...