use bytes.IndexByte

Signed-off-by: Grant Linville <[email protected]>

Author: g-linville

pkg/builtin/builtin.go

@@ -491,7 +491,7 @@ func SysRead(_ context.Context, _ []string, input string, _ chan<- string) (stri
 	}
 
 	// Assume the file is not text if it contains a null byte
-	if bytes.Contains(data, []byte{0}) {
+	if bytes.IndexByte(data, 0) != -1 {
 		return fmt.Sprintf("The file %s cannot be read because it is not a plaintext file", params.Filename), nil
 	}