Hmm...  Looks like a unified diff to me...
The text leading up to this was:
--------------------------
|diff -up dwm-a/dwm.c dwm-b/dwm.c
|--- dwm-a/dwm.c	2019-01-15 19:59:21.363468198 +0100
|+++ dwm-b/dwm.c	2015-11-08 23:39:37.000000000 +0100
--------------------------
Patching file dwm.c using Plan A...
Hunk #1 succeeded at 720.
done