Merge pull request #8 from alecthomas/master

Prevent panic when bad data is returned from Secrets().

basic.go

@@ -37,7 +37,7 @@ func (a *BasicAuth) CheckAuth(r *http.Request) string {
 	if passwd == "" {
 		return ""
 	}
-	if passwd[:5] == "{SHA}" {
+	if strings.HasPrefix(passwd, "{SHA}") {
 		d := sha1.New()
 		d.Write([]byte(pair[1]))
 		if passwd[5:] != base64.StdEncoding.EncodeToString(d.Sum(nil)) {