findDisconnectedObjects not protected against other GC's

If a GC operation (markForCollection, epoch GC) executes while a
SystemRepository>>findDisconnectedObjects is running, the results returned
from the findDisconnectedObjects may be inconsistent.

Workaround:

Disable epoch GC and make sure that no one is using markForCollection
while performing findDisconnectedObjects.

Epoch GC can be disabled by setting the GcUser's UserGlobals parameter
#epochGcEnabled to false.