EditorManager: Remove wrong warning

The mime type hierarchy is not a tree (e.g. diamond shape inheritence is
ok), so if we traverse a parent hierarchy and encounter a mime type
twice, that is not an indicator for an actual loop / wrong hierarchy.

Change-Id: Ic116deac5a03b9692e2267252598db6d8721f39e
Reviewed-by: David Schulz <david.schulz@theqtcompany.com>

src/plugins/coreplugin/editormanager/editormanager.cpp

@@ -2543,8 +2543,6 @@ static void mimeTypeFactoryLookup(const Utils::MimeType &mimeType,
                 seen.insert(parent.name());
                 if (seen.size() != seenSize) // not seen before, so add
                     queue.append(parent);
-                else
-                    qWarning("MimeTypes: Parent hierarchy loop detected for '%s'!", qPrintable(parent.name()));
             }
         }
     }