[INFRA-100] - Do not rename components to existing names

Signed-off-by: Oleg Nenashev <o.v.nenashev@gmail.com>

src/main/java/org/jenkinsci/jira_scraper/JiraScraper.java

@@ -65,6 +65,18 @@ public void renameComponent(String projectKey, String oldName, String newName)
         BasicComponent c = getBasicComponent(projectKey, oldName);
         Component comp = getComponent(c);
 
+        // Check the existance of the new component
+        BasicComponent newComponent = null;
+        try {
+            newComponent = getBasicComponent(projectKey, newName);
+        } catch (IOException cannotFindTheComponent) {
+            // All is OK
+        }
+        if (newComponent != null) {
+            throw new IOException("Unable to rename component " + oldName + 
+                    ". Component " + newName + " already exists");
+        }
+
         AssigneeInfo info = comp.getAssigneeInfo();
         AssigneeType assigneeType = info != null ? info.getAssigneeType() : null;
         BasicUser leadUser = info != null ? info.getAssignee() : null;