skip tests on tip

.travis.yml

@@ -1,10 +1,9 @@
 language: go
 go_import_path: github.com/pkg/errors
 go:
-  - 1.5.4
   - 1.4.3
+  - 1.5.4
   - 1.6.1
-  - tip
 
 script:
   - go test -v ./...

example_test.go

@@ -18,7 +18,7 @@ func ExampleNew_Fprint() {
 	err := errors.New("whoops")
 	errors.Fprint(os.Stdout, err)
 
-	// Output: github.com/pkg/errors/example_test.go:5: whoops
+	// Output: github.com/pkg/errors/example_test.go:18: whoops
 }
 
 func ExampleWrap() {