How do I configure a port to get a specific sourceforge commit?

I'm trying to update graphics/netpbm to an actively maintained repo (PR 
262212). I'm told by some that this is the current best choice:

     https://sourceforge.net/projects/netpbm/

Unfortunately its idea of "release management" is less than ideal.

Let's say I browse this commit log:

     https://sourceforge.net/p/netpbm/code/4616/log/?path=/advanced

and decide that release 11.03.04/commit r4606 is interesting. I can 
download it if I click on "Tree" for that commit and then "Download 
Snapshot" it gives me this as the "direct link":

 
https://sourceforge.net/code-snapshots/svn/n/ne/netpbm/code/netpbm-code-r4606-advanced.zip

This definitely works. But I don't find an existing port that uses 
sourceforge with a specific commit and no combination of 
"MASTERSITES=SF..." I've tried works.

I have something that does work but it's a horrible hack, essentially:

     DISTVERSION=   11.03.04
     MASTER_SITES= 
${MASTER_SITE_SOURCEFORGE:S,/project/%SUBDIR%/,/code-snapshots/svn/n/ne/netpbm/code/,}
     DISTNAME=      netpbm-code-r4606-advanced
     USES=          zip

Is there a less hacky way to do this?

		Craig