s3a file rename does double HEAD or LIST on source file/dir

going to add this as a v2 issue, though really it's been latent.

when you do a rename() we do a getFileStatus call to get the list/file status..if this is a dir that's a single LIST; a file then it'll be LIST + HEAD.

when the actual copy is kicked off,

• if the source is a dir, then a duplicate LIST is initiated straight afterwards.
• FIle: there's a second HEAD to get the metadata for the copy

Proposed.

• LIST initiates a full list, and if it returns a list of objects, that list iterator is passed in to rename.
• full result of HEAD preserved and passed down to copyFile()

will cut out one round trip regardless of source type