fix handling of redirect from asset download

vendor/github.com/golang/protobuf/proto/text_parser.go

@@ -119,14 +119,6 @@ func isWhitespace(c byte) bool {
 	return false
 }
 
-func isQuote(c byte) bool {
-	switch c {
-	case '"', '\'':
-		return true
-	}
-	return false
-}
-
 func (p *textParser) skipWhitespace() {
 	i := 0
 	for i < len(p.s) && (isWhitespace(p.s[i]) || p.s[i] == '#') {
@@ -341,13 +333,13 @@ func (p *textParser) next() *token {
 	p.advance()
 	if p.done {
 		p.cur.value = ""
-	} else if len(p.cur.value) > 0 && isQuote(p.cur.value[0]) {
+	} else if len(p.cur.value) > 0 && p.cur.value[0] == '"' {
 		// Look for multiple quoted strings separated by whitespace,
 		// and concatenate them.
 		cat := p.cur
 		for {
 			p.skipWhitespace()
-			if p.done || !isQuote(p.s[0]) {
+			if p.done || p.s[0] != '"' {
 				break
 			}
 			p.advance()