Don't add the same milestones #40

Author: junichi11

src/main/java/com/junichi11/netbeans/modules/github/issues/issue/ui/GitHubIssuePanel.java

@@ -517,7 +517,7 @@ private void setMilestoneSelected(Milestone milestone) {
             }
             if (m.getNumber() == milestone.getNumber()) {
                 milestoneComboBox.setSelectedItem(m);
-                break;
+                return;
             }
         }