We have a test already: org.infinispan.query.persistence.SharedCacheLoaderQueryIndexTest

It was disabled for other reasons, mistakenly identified as a testsuite error.

The case is simple: the test is configured in such a way to trigger a newly joining node using an in-memory dummy CacheStore which is shared by both nodes, with preloading enabled.
Index storage is not shared though: uses ram.
During the preload phase of the new node, the preload code issues the SKIP_INDEXING flag.. which in this case it should not.