In this commit:
cbf3d43561358149 drive: fix missing items when listing using --fast-list / ListR
We introduced a bug where under specific circumstances it could cause
a "panic: send on closed channel".
This was caused by:
- rclone engaging the workaround from the commit above
- one of the listing routines returning an error
- this caused the `in` channel to be closed to stop the readers
- however the workaround was recycling stuff into the `in` channel at the time
- hence the panic on closed channel
This fix factors out the sending to the `in` channel into `sendJob`
and calls this both from the master go routine and the list
runners. `sendJob` detects the `in` channel being closed properly and
also deals correctly with contention on the `in` channel.
Fixes#4511
068cfdaa00