project configuration: avoid infinite loops when deleting library root

Avoid infinite loop even if 'Library.ModifiableModel::removeRoot' always returns true because of a bug (see IDEA-182159). If there are several identical roots in a library it should be ok to remove them one by one.

java/idea-ui/src/com/intellij/openapi/roots/ui/configuration/libraryEditor/ExistingLibraryEditor.java

@@ -189,11 +189,7 @@ public class ExistingLibraryEditor extends LibraryEditorBase implements Disposab
 
   @Override
   public void removeRoot(@NotNull String url, @NotNull OrderRootType rootType) {
-    boolean removed;
-    do {
-      removed = getModel().removeRoot(url, rootType);
-    }
-    while (removed);
+    getModel().removeRoot(url, rootType);
   }
 
   @Override