Hmm...  Looks like a unified diff to me...
The text leading up to this was:
--------------------------
|diff -up dwm-6.2-original/config.def.h dwm-6.2-modified/config.def.h
|--- dwm-6.2-original/config.def.h	2019-02-02 14:55:28.000000000 +0200
|+++ dwm-6.2-modified/config.def.h	2019-11-18 17:46:56.829143140 +0200
--------------------------
Patching file config.def.h using Plan A...
Hunk #1 succeeded at 56.
done