Bump purell to v1.1.1

Signed-off-by: He Xiaoxi <xxhe@alauda.io>

vendor/github.com/PuerkitoBio/purell/.travis.yml

@@ -1,7 +1,12 @@
 language: go
 
 go:
-    - 1.4
-    - 1.5
-    - 1.6
+    - 1.4.x
+    - 1.5.x
+    - 1.6.x
+    - 1.7.x
+    - 1.8.x
+    - 1.9.x
+    - "1.10.x"
+    - "1.11.x"
     - tip

vendor/github.com/PuerkitoBio/purell/README.md

@@ -4,7 +4,7 @@ Purell is a tiny Go library to normalize URLs. It returns a pure URL. Pure-ell.
 
 Based on the [wikipedia paper][wiki] and the [RFC 3986 document][rfc].
 
-[![build status](https://secure.travis-ci.org/PuerkitoBio/purell.png)](http://travis-ci.org/PuerkitoBio/purell)
+[![build status](https://travis-ci.org/PuerkitoBio/purell.svg?branch=master)](http://travis-ci.org/PuerkitoBio/purell)
 
 ## Install
 
@@ -12,6 +12,7 @@ Based on the [wikipedia paper][wiki] and the [RFC 3986 document][rfc].
 
 ## Changelog
 
+*    **v1.1.1** : Fix failing test due to Go1.12 changes (thanks to @ianlancetaylor).
 *    **2016-11-14 (v1.1.0)** : IDN: Conform to RFC 5895: Fold character width (thanks to @beeker1121).
 *    **2016-07-27 (v1.0.0)** : Normalize IDN to ASCII (thanks to @zenovich).
 *    **2015-02-08** : Add fix for relative paths issue ([PR #5][pr5]) and add fix for unnecessary encoding of reserved characters ([see issue #7][iss7]).

vendor/github.com/PuerkitoBio/purell/purell.go

@@ -299,7 +299,7 @@ func sortQuery(u *url.URL) {
 	if len(q) > 0 {
 		arKeys := make([]string, len(q))
 		i := 0
-		for k, _ := range q {
+		for k := range q {
 			arKeys[i] = k
 			i++
 		}