internal/testenv: skip network tests only when -short is specified

Change-Id: I157879f5204d543eb3fc81c212d563b146473ba8
Reviewed-on: https://go-review.googlesource.com/11232Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>

src/internal/testenv/testenv.go

@@ -86,5 +86,7 @@ func HasExternalNetwork() bool {
 // external (non-localhost) networks.
 // If not, MustHaveExternalNetwork calls t.Skip with an explanation.
 func MustHaveExternalNetwork(t *testing.T) {
-	t.Skipf("skipping test: no external network in -short mode")
+	if testing.Short() {
+		t.Skipf("skipping test: no external network in -short mode")
+	}
 }