solrcore.properties is not reloaded when core is reloaded

When I change solrcore.properties for a core, and then reload the core, the previous values of the properties in that file are still in effect. If I unload the core and then add it back, in the “Core Admin” section of the admin UI, then the changes in solrcore.properties do take effect.

My specific test case is a DataImportHandler where db-data-config.xml uses a property to decide which DB host to talk to:

<dataSource driver="org.postgresql.Driver" name="meta" url="jdbc:postgresql://${dbhost}/${solr.core.name}" .../>

When I change that dbhost property in solrcore.properties and reload the core, the next dataimport operation still connects to the previous DB host. Reloading the dataimport config does not help. I have to unload the core (or fully restart the whole Solr) for the properties change to take effect.