This change checks the context whenever rclone might retry, and
doesn't retry if the current context has an error.
This fixes the pathological behaviour of `--max-duration` refusing to
exit because all the context deadline exceeded errors were being
retried.
This unfortunately meant changing the shouldRetry logic in every
backend and doing a lot of context propagation.
See: https://forum.rclone.org/t/add-flag-to-exit-immediately-when-max-duration-reached/22723
This is done by making fs.Config private and attaching it to the
context instead.
The Config should be obtained with fs.GetConfig and fs.AddConfig
should be used to get a new mutable config that can be changed.
Before this change we counted the final summary error as an error,
producing confusing log messages like:
Failed to check with 54 errors: last error was: 53 differences found
This change marks the summary error as already being counted, so the
error message becomes:
Failed to check with 53 errors: last error was: 53 differences found
This change also returns a listing failure in preference to a summary error.
See: https://forum.rclone.org/t/slow-checksum-validation/19763/22
This is preparation for getting the Accounting to check the context,
buf first we need to get it in place. Since this is one of those
changes that makes lots of noise, this is in a seperate commit.
