From f6390abad74f0cbff79fcb73efa7306d2c89e63e Mon Sep 17 00:00:00 2001
From: Hajime Hoshi <hajimehoshi@gmail.com>
Date: Mon, 25 Nov 2019 22:24:33 +0900
Subject: [PATCH] png: Update for Go 1.13

---
 internal/png/stdlibreader.go | 2 +-
 internal/png/stdlibwriter.go | 1 -
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/internal/png/stdlibreader.go b/internal/png/stdlibreader.go
index ca9878064..acaded255 100644
--- a/internal/png/stdlibreader.go
+++ b/internal/png/stdlibreader.go
@@ -708,7 +708,7 @@ func (d *decoder) readImagePass(r io.Reader, pass int, allocateOnly bool) (image
 				}
 			}
 		case cbP8:
-			if len(paletted.Palette) != 255 {
+			if len(paletted.Palette) != 256 {
 				for x := 0; x < width; x++ {
 					if len(paletted.Palette) <= int(cdat[x]) {
 						paletted.Palette = paletted.Palette[:int(cdat[x])+1]
diff --git a/internal/png/stdlibwriter.go b/internal/png/stdlibwriter.go
index a34b85add..f573b96e5 100644
--- a/internal/png/stdlibwriter.go
+++ b/internal/png/stdlibwriter.go
@@ -290,7 +290,6 @@ func filter(cr *[nFilter][]byte, pr []byte, bpp int) int {
 		}
 	}
 	if sum < best {
-		best = sum
 		filter = ftAverage
 	}