Same functionality, but implemented with atomicwriter. There's a slight
difference in error-messages produced (but can be adjusted if we want).
Before:
docker container export -o ./no/such/foo mycontainer
failed to export container: invalid output path: directory "no/such" does not exist
docker container export -o /no/permissions mycontainer
failed to export container: stat /no/permissions: permission denied
After:
docker container export -o ./no/such/foo mycontainer
failed to export container: invalid file path: stat no/such: no such file or directory
docker container export -o /no/permissions mycontainer
failed to export container: failed to stat output path: lstat /no/permissions: permission denied
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
b8bcf6f5ad