Hmm...  Looks like a unified diff to me...
The text leading up to this was:
--------------------------
|diff -up dwm-6.0/dwm.c dwm-6.0-resizecorners/dwm.c
|--- dwm-6.0/dwm.c	2011-12-19 15:02:46.000000000 +0000
|+++ dwm-6.0-resizecorners/dwm.c	2015-05-12 23:31:10.803508011 +0000
--------------------------
Patching file dwm.c using Plan A...
Hunk #1 succeeded at 1364.
Hunk #2 succeeded at 1402.
Hunk #3 succeeded at 1414.
done