From BF-35516 several issues were discovered with the framework that hamper determining the underlying cause, namely:

 - Errors copying files are not propagated to the test

 - File copies can happen concurrently (for the same file) potentially introducing races

 - Cursors are closed before files are copied, which is potentially an API violation

This ticket aims to fix these shortcomings, unfortunately we arent sure if this is a true fix for the underlying BF but we'll at least be in a better position if it happens again.