MetadataBasedProductMover to handle when the source and destinations match

I was trying to move an entire ProductType using the MetadataBasedProductMover class. Everything as going swell until it reached a product that was missing from the archive.

When I restarted the move MetadataBasedProductMover started complaining about the source and destination for the move are the same, and it would halt with the following errors:

INFO: Moving product: [blah.txt] from: [/Users/cgoodale/files/moved/null] to: [/Users/cgoodale/files/moved/null]
Exception in thread "main" org.apache.oodt.cas.filemgr.structs.exceptions.DataTransferException: java.lang.Exception: org.apache.oodt.cas.filemgr.structs.exceptions.DataTransferException: cannot move product: [blah.txt] to same location: file:/Users/cgoodale/files/moved/null
at org.apache.oodt.cas.filemgr.system.XmlRpcFileManagerClient.moveProduct(XmlRpcFileManagerClient.java:305)
at org.apache.oodt.cas.filemgr.tools.MetadataBasedProductMover.moveProducts(MetadataBasedProductMover.java:113)
at org.apache.oodt.cas.filemgr.tools.MetadataBasedProductMover.moveProducts(MetadataBasedProductMover.java:142)
at org.apache.oodt.cas.filemgr.tools.MetadataBasedProductMover.main(MetadataBasedProductMover.java:172)

I have written up a small patch to MetadataBasedProductMover that does a check before attempting to perform the move. Thanks to Michael Joyce for his help on this.