Use 307 redirects

This is to see if we can send non-GET requests through SSO.

httpsso/handler_test.go

@@ -46,8 +46,8 @@ func makeAuthRequest(t testing.TB, c *http.Client, base, path, service, domain s
 	if err != nil {
 		t.Fatalf("Get(%s): %v", path, err)
 	}
-	if resp.StatusCode != http.StatusFound {
-		t.Fatalf("Get(%s) expected 302, got %d", path, resp.StatusCode)
+	if resp.StatusCode != http.StatusTemporaryRedirect {
+		t.Fatalf("Get(%s) expected 307, got %d", path, resp.StatusCode)
 	}
 	loc, err := url.Parse(resp.Header.Get("Location"))
 	if err != nil {
@@ -78,8 +78,8 @@ func makeAuthRequest(t testing.TB, c *http.Client, base, path, service, domain s
 	if err != nil {
 		t.Fatal("Get(/sso_login):", err)
 	}
-	if resp.StatusCode != http.StatusFound {
-		t.Fatalf("Get(/sso_login) expected 302, got %d", resp.StatusCode)
+	if resp.StatusCode != http.StatusTemporaryRedirect {
+		t.Fatalf("Get(/sso_login) expected 307, got %d", resp.StatusCode)
 	}
 	resp.Body.Close()
 	if s := resp.Header.Get("Location"); s != destURL {