Fix PR-webhook issue where Label-data is stale (#3486) (#3510)

* Fix PR-webhook issue where Label-data is stale

* Conventions \o/

* logs are nice if they're consistent...

models/issue.go

@@ -235,7 +235,11 @@ func (i *Issue) HasLabel(labelID int64) bool {
 func (issue *Issue) sendLabelUpdatedWebhook(doer *User) {
 	var err error
 	if issue.IsPull {
-		issue.PullRequest.Issue = issue
+		err = issue.PullRequest.LoadIssue()
+		if err != nil {
+			log.Error(4, "LoadIssue: %v", err)
+			return
+		}
 		err = PrepareWebhooks(issue.Repo, HOOK_EVENT_PULL_REQUEST, &api.PullRequestPayload{
 			Action:      api.HOOK_ISSUE_LABEL_UPDATED,
 			Index:       issue.Index,
@@ -335,7 +339,11 @@ func (issue *Issue) ClearLabels(doer *User) (err error) {
 	}
 
 	if issue.IsPull {
-		issue.PullRequest.Issue = issue
+		err = issue.PullRequest.LoadIssue()
+		if err != nil {
+			log.Error(4, "LoadIssue: %v", err)
+			return
+		}
 		err = PrepareWebhooks(issue.Repo, HOOK_EVENT_PULL_REQUEST, &api.PullRequestPayload{
 			Action:      api.HOOK_ISSUE_LABEL_CLEARED,
 			Index:       issue.Index,