[release-branch.go1.10-security] net: pass if at least one matching entry in TestLookupGmailTXT

Fixes #29698

Change-Id: I0531c0a274b120af8871aa2f5975744ff6c912a3
Reviewed-on: https://go-review.googlesource.com/c/157638
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-on: https://team-review.git.corp.google.com/c/401204
Reviewed-by: Filippo Valsorda <valsorda@google.com>

src/net/lookup_test.go

diff --git a/src/net/lookup_test.go b/src/net/lookup_test.go
index 24787cc..01901e6 100644
--- a/src/net/lookup_test.go
+++ b/src/net/lookup_test.go
@@ -184,11 +184,16 @@
 		if len(txts) == 0 {
 			t.Error("got no record")
 		}
+		found := false
 		for _, txt := range txts {
-			if !strings.Contains(txt, tt.txt) || (!strings.HasSuffix(txt, tt.host) && !strings.HasSuffix(txt, tt.host+".")) {
-				t.Errorf("got %s; want a record containing %s, %s", txt, tt.txt, tt.host)
+			if strings.Contains(txt, tt.txt) && (strings.HasSuffix(txt, tt.host) || strings.HasSuffix(txt, tt.host+".")) {
+				found = true
+				break
 			}
 		}
+		if !found {
+			t.Errorf("got %v; want a record containing %s, %s", txts, tt.txt, tt.host)
+		}
 	}
 }