cmd/go: check MustHaveExternalNetwork before `go get` tests

Also change a couple of `go get` tests to use MustHaveExternalNetwork
rather than checking testing.Short.

Change-Id: I98ccc05b8b0354f1b7486e28dac5f8341c342a07
Reviewed-on: https://go-review.googlesource.com/33802
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/cmd/go/go_test.go

@@ -1700,6 +1700,8 @@ func TestMissingGOPATHEnvShowsDefault(t *testing.T) {
 
 // Test go get missing GOPATH causes go get to warn if directory doesn't exist.
 func TestMissingGOPATHGetWarnsIfNotExists(t *testing.T) {
+	testenv.MustHaveExternalNetwork(t)
+
 	if _, err := exec.LookPath("git"); err != nil {
 		t.Skip("skipping because git binary not found")
 	}
@@ -1727,6 +1729,8 @@ func TestMissingGOPATHGetWarnsIfNotExists(t *testing.T) {
 
 // Test go get missing GOPATH causes no warning if directory exists.
 func TestMissingGOPATHGetDoesntWarnIfExists(t *testing.T) {
+	testenv.MustHaveExternalNetwork(t)
+
 	if _, err := exec.LookPath("git"); err != nil {
 		t.Skip("skipping because git binary not found")
 	}
@@ -1757,6 +1761,8 @@ func TestMissingGOPATHGetDoesntWarnIfExists(t *testing.T) {
 
 // Test go get missing GOPATH fails if pointed file is not a directory.
 func TestMissingGOPATHGetFailsIfItsNotDirectory(t *testing.T) {
+	testenv.MustHaveExternalNetwork(t)
+
 	tg := testgo(t)
 	defer tg.cleanup()
 
@@ -2067,9 +2073,7 @@ func TestCaseCollisions(t *testing.T) {
 
 // Issue 8181.
 func TestGoGetDashTIssue8181(t *testing.T) {
-	if testing.Short() {
-		t.Skip("skipping test that uses network in short mode")
-	}
+	testenv.MustHaveExternalNetwork(t)
 
 	tg := testgo(t)
 	defer tg.cleanup()
@@ -2083,9 +2087,7 @@ func TestGoGetDashTIssue8181(t *testing.T) {
 
 func TestIssue11307(t *testing.T) {
 	// go get -u was not working except in checkout directory
-	if testing.Short() {
-		t.Skip("skipping test that uses network in short mode")
-	}
+	testenv.MustHaveExternalNetwork(t)
 
 	tg := testgo(t)
 	defer tg.cleanup()