SitemapItem does not inherit Mount-configured defaultsitemapitemhandlers

Consider the following scenario:

• Mount which points site configuration "/hst:hst/hst:configurations/mysiteconfig"
• Mount has hst:defaulsitemapitemhandlerids set to form-component-injector
• site map item "/contact/default" in the configuration that doesn't have hst:sitemapitemhandlerids property set

expected behavior:

• configured sitemapitemhandler gets fired

observed behavior:

• configured sitemapitemhandler does not get fired.

Further inspection shows (when putting a break point in the hstfilter before it handlers the handlers):

• SitemapItemService doesn't have any sitemapitemhandlers
• the resolved mount of the resolvedsitemapitem does have defaultsitemapitemhandlers

I think that something goes wrong when loading the HST configuration.