vagrant download: Fix 'invalid cross-device link'

If the unpacked directory is on a different device from the download
destination (happens on tests if the code is in encrypted home),
rename()ing the file would fail. Use move() instead.

reprounzip-vagrant/reprounzip/unpackers/vagrant/__init__.py

@@ -707,7 +707,7 @@ def download(self, remote_path, local_path):
 
         # Move file to final destination
         try:
-            ltemp.rename(local_path)
+            ltemp.move(local_path)
         except OSError as e:
             logger.critical("Couldn't download output file: %s\n%s",
                             remote_path, str(e))