Symlink 'current' replaced by file current_case

The  'current' symlink in the 'storage' directory is pointing to the current case. 
When the storage folder is copied, the 'current' symlink is sometimes replaced by the actual content of the current case. A guess is that it happens when the copy operation crosses disk partitions. 

The symlink is now replaced by a file 'current_case'. The file has one entry; the name of the current case. 
If the file is present on disk, current case is read from file. If the file is not present and the symlink is present, current case is resolved by reading the symlink, the 'current_case' file is written and the symlink is deleted.