Fixed conveyor move logic to skip directories that already existed in the spool

Conveyor's retrieval before ingestion:

1. Grabs a directory list from spool
2. Removes those that are symlinks pointing to QA
3. Moves the directories from QA to spool

Step 2 skips directories that are not symlinks but step 3 still tried to move them. Now step 3 will skip those same directories.