Similar to CL
3814041 that fixed the same issue in strings.
Fixes #6941.
R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/
41490045
// FieldsFunc interprets s as a sequence of UTF-8-encoded Unicode code points.
// It splits the slice s at each run of code points c satisfying f(c) and
-// returns a slice of subslices of s. If no code points in s satisfy f(c), an
-// empty slice is returned.
+// returns a slice of subslices of s. If all code points in s satisfy f(c), or
+// len(s) == 0, an empty slice is returned.
func FieldsFunc(s []byte, f func(rune) bool) [][]byte {
n := 0
inField := false