Fix submit queue when there are multiple LGTMs

contrib/submit-queue/github/github.go

@@ -111,9 +111,11 @@ func validateLGTMAfterPush(client *github.Client, user, project string, pr *gith
 	for ix := range events {
 		event := &events[ix]
 		if *event.Event == "labeled" && *event.Label.Name == "lgtm" {
+			if lgtmTime == nil || event.CreatedAt.After(*lgtmTime) {
 				lgtmTime = event.CreatedAt
 			}
 		}
+	}
 	if lgtmTime == nil {
 		return false, fmt.Errorf("Couldn't find time for LGTM label, this shouldn't happen, skipping PR: %d", *pr.Number)
 	}

contrib/submit-queue/github/github_test.go

@@ -424,6 +424,60 @@ func TestValidateLGTMAfterPush(t *testing.T) {
 			lastModified: time.Unix(11, 0),
 			shouldPass:   false,
 		},
+		{
+			issueEvents: []github.IssueEvent{
+				{
+					Event: stringPtr("labeled"),
+					Label: &github.Label{
+						Name: stringPtr("lgtm"),
+					},
+					CreatedAt: timePtr(time.Unix(12, 0)),
+				},
+				{
+					Event: stringPtr("labeled"),
+					Label: &github.Label{
+						Name: stringPtr("lgtm"),
+					},
+					CreatedAt: timePtr(time.Unix(11, 0)),
+				},
+				{
+					Event: stringPtr("labeled"),
+					Label: &github.Label{
+						Name: stringPtr("lgtm"),
+					},
+					CreatedAt: timePtr(time.Unix(10, 0)),
+				},
+			},
+			lastModified: time.Unix(11, 0),
+			shouldPass:   true,
+		},
+		{
+			issueEvents: []github.IssueEvent{
+				{
+					Event: stringPtr("labeled"),
+					Label: &github.Label{
+						Name: stringPtr("lgtm"),
+					},
+					CreatedAt: timePtr(time.Unix(10, 0)),
+				},
+				{
+					Event: stringPtr("labeled"),
+					Label: &github.Label{
+						Name: stringPtr("lgtm"),
+					},
+					CreatedAt: timePtr(time.Unix(11, 0)),
+				},
+				{
+					Event: stringPtr("labeled"),
+					Label: &github.Label{
+						Name: stringPtr("lgtm"),
+					},
+					CreatedAt: timePtr(time.Unix(12, 0)),
+				},
+			},
+			lastModified: time.Unix(11, 0),
+			shouldPass:   true,
+		},
 	}
 	for _, test := range tests {
 		client, server, mux := initTest()