VDR Streamdev Plugin

So I'm a little confused here... I've been having issues with externremux and stumbled across commit d556ee7fdaea2ade54e9b6c383f44fa88a483f8 which looks like it will fix exactly the issue I'm having, However git seems to be behaving incredibly oddly, in that if I pull the repository as recommended here with the following command
git clone git://projects.vdr-developer.org/vdr-plugin-streamdev.git
Then I do indeed appear to have the latest version, which compiles against vdr 2.3.1, and therefore include the extern.c patch.

The odd thing being in HISTORY, I have the line
- Don't abort externremux when internal read buffer is empty

So the first file in the commit has been modified correctly, however the more import file that is extern.c, has not been modified?!

Moving to that specific commit with
git checkout dd556ee7fdaea2ade54e9b6c383f44fa88a483f8
Shows the same, HISTORY is modified, but extern.c not touched. If you browse the repository online, again you can see the latest extern.c has not had the fix applied.

I've checked a couple more commits from around the same time and they seem to be correctly applied in the latest commit, so why is the extern.c patch being left out in the cold? :)