convert big dir to repo without copying

[GoogleCodeExporter]

Enhancement request: 

Create a variation of import that converts an existing large backup directory 
into a repo, without copying any files. 

I guess it could create a repo on the same drive, and simply move files into 
the repo instead of copying them. 

Example use case: 

You have an existing large video/photo store on an external drive (as backup). 
You have the same files on your internal drive, where you organize them into 
many subfolders, and do a lot of renaming. Now you can't easily update the 
existing backup; the only simple way is to copy all of the local dirs to a new 
backup. 

But if you could convert the old backup to a boar repo, then boar could make 
that backup reflect the new folder structure, and add new files without 
duplication. And if boar could create that repo without copying files, you 
would avoid extra copying completely.

Original issue reported on code.google.com by jon...@gmail.com on 30 Dec 2013 at 7:25