LGTM. The comment below is just a suggestion, feel free to reword/ignore
it.
https://codereview.appspot.com/6849128/diff/10001/src/pkg/bytes/buffer.go
File src/pkg/bytes/buffer.go (right):
https://codereview.appspot.com/6849128/diff/10001/src/pkg/bytes/buffer.go#newcode363
src/pkg/bytes/buffer.go:363: slice, err := b.readSlice(delim)
// copy slice as its backing array may be overwritten.
https://codereview.appspot.com/6849128/
