Before this change the --local-no-updated flag would not error if the
files changed in size during the transfer. The file could still be
read beyond the size advertised though which caused problems with
certain backends.
After this change we attempt to provide a consistent view of the file
once it has been opened.
Once the file has had stat() called on it for the first time we
- Only transfer the size that stat gave
- Only checksum the size that stat gave
- Don't update the stat info for the file
This means that files that are extending can be transferred - rclone
will transfer the length it saw the first time it listed the file.
See: https://forum.rclone.org/t/transport-connection-broken/16494/21
0bcf4769fe