Borg upgrade fails, if repository folder is mounted on other partition than parent folder

[fabefour]

borg upgrade tries to create a temp folder "borg.upgrade-timestamp" outside of the repository folder.
If the repository folder and the parent folder are not on the same partition this fails as the hardlinks cannot be created.

Local Exception.
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/borg/archiver.py", line 2052, in main
    exit_code = archiver.run(args)
  File "/usr/lib/python3/dist-packages/borg/archiver.py", line 1997, in run
    return func(args)
  File "/usr/lib/python3/dist-packages/borg/archiver.py", line 74, in wrapper
    return method(self, args, repository=None, **kwargs)
  File "/usr/lib/python3/dist-packages/borg/archiver.py", line 769, in do_upgrade
    repo.upgrade(args.dry_run, inplace=args.inplace, progress=args.progress)
  File "/usr/lib/python3/dist-packages/borg/upgrader.py", line 38, in upgrade
    shutil.copytree(self.path, backup, copy_function=os.link)
  File "/usr/lib/python3.4/shutil.py", line 342, in copytree
    raise Error(errors)
shutil.Error: [('/mnt/raid/borg/hints.50756', '/mnt/raid/borg.upgrade-2017-01-19-10:01:17/hints.50756', "[Errno 18] Invalid cross-device link: '/mnt/raid/borg/hints.50756' -> '/mnt/raid/borg.upgrade-2017-01-19-10:01:17/hints.50756'"), ('/mnt/raid/borg/README', '/mnt/raid/borg.upgrade-2017-01-19-10:01:17/README', "[Errno 18] Invalid cross-device link: '/mnt/raid/borg/README' -> '/mnt/raid/borg.upgrade-2017-01-19-10:01:17/README'"), ...

[ThomasWaldmann]

Well, the easiest way to avoid that is to not put stuff directly in the root directory of filesystems, but always use a subdirectory.

Of course, for already existing stuff this does not help much (you could still move it manually though).

borg upgrade --inplace does not do that btw (so it should work), but is a bit riskier as it does not do that hardlink-copy.