"Keep this build forever" button not visible if BuildDiscarder other than LogRotator is configured

The button "Keep this build forever" is not visible in the build summary page when a BuildDiscarder other than LogRotator is configured. I don't think this is intentionally.

The problem is in Jelly file core\src\main\resources\hudson\model\Run\logKeep.jelly, line 30:

<j:if test="${it.parent.logRotator!=null and it.canToggleLogKeep()}">

Should be fixed to:

<j:if test="${it.parent.buildDiscarder!=null and it.canToggleLogKeep()}">