jobs are not reserved but the tube is being watched

I'm using `@beanstalk.jobs.process!` to automatically process the jobs. But I find that, after some time, my scripts are not getting any jobs.

Issuing `stats-tube` command shows that there are `x` number of clients watching the tube, but there are 0 clients in `waiting` state. The number of jobs keep increasing, but none of the clients receives any job.

Sample out of `stats-tube` below

```
stats-tube email.send.v1
OK 263

---
name: email.send.v1
current-jobs-urgent: 0
current-jobs-ready: 10
current-jobs-reserved: 0
current-jobs-delayed: 0
current-jobs-buried: 0
total-jobs: 196704
current-using: 0
current-watching: 1
current-waiting: 0
cmd-pause-tube: 0
pause: 0
pause-time-left: 0
```

If I stop and start my scripts, jobs get processed. Any input on this will helpful

Start by reproducing the stalled processing described with @beanstalk.jobs.process! and inspect the corresponding stats-tube output, especially current-watching and current-waiting. Trace the job reservation and waiting lifecycle to determine why processing stops; done means ready jobs continue to be reserved and processed without restarting the scripts.

Written by the indexing model from the issue text.