mv -t: question about behavior when target is moved away

[Voelker, Bernhard]

Just about a corner case:
when the target directory is renamed during a `mv -t` run,
then the behaviour is different than if it wasn't there at
program start.

Consider the following example:

  n=20000
  mkdir target
  seq $n | xargs touch
  seq $n | xargs mv --target-directory=target &
  sleep 1
  mv -v target target.renamed

What happens is that after the target has been renamed,
mv starts complaining about every file which couldn't be
moved:

  `target' -> `target.renamed'
  mv: cannot move `7484' to `target/7484': No such file or directory
  mv: cannot move `7485' to `target/7485': No such file or directory
  ...

while after some time, when xargs has executed a new mv process,
that one refuses to start with:

  mv: accessing `target': No such file or directory

I feel somehow strange about the former error message.

Well, if the target appears again during such a run, then
moving continues normally. So maybe trying to continue is
right, but in conjunction with xargs, it is strange that
mv sometimes tries to continue and sometimes not.

As --target-directory is by design for use with xargs,
I would have expected a more consistent behavior:
maybe break out of the loop with the same message
as in the latter case.

Is this behavior on purpose / a feature / required by some
standard?

Have a nice day,
Berny