travis: Test go1.13 and drop go1.11.

.travis.yml

@@ -5,25 +5,25 @@ env:
 matrix:
   include:
     - os: linux
-      go: 1.12.x
+      go: 1.13.x
       cache:
         directories:
           - $HOME/.cache/go-build
           - $HOME/go/pkg/mod
     - os: linux
-      go: 1.11.x
-      cache:
-        directories:
-          - $HOME/.cache/go-build
-          - $HOME/go/pkg/mod
-    - os: osx
       go: 1.12.x
       cache:
         directories:
           - $HOME/.cache/go-build
           - $HOME/go/pkg/mod
     - os: osx
-      go: 1.11.x
+      go: 1.13.x
+      cache:
+        directories:
+          - $HOME/.cache/go-build
+          - $HOME/go/pkg/mod
+    - os: osx
+      go: 1.12.x
       cache:
         directories:
           - $HOME/Library/Caches/go-build

config_test.go

@@ -5,7 +5,6 @@
 package main
 
 import (
-	"flag"
 	"os"
 	"strings"
 	"testing"
@@ -76,6 +75,5 @@ func TestAltDNSNamesWithArg(t *testing.T) {
 // init parses the -test.* flags from the command line arguments list and then
 // removes them to allow go-flags tests to succeed.
 func init() {
-	flag.Parse()
 	os.Args = os.Args[:1]
 }