Schedule one-time job execution after a certain time

I am facing difficulties when using [at](https://linux.die.net/man/1/at) to schedule a one-time job after a certain time like this:
```

at -f ./my-script.sh now + 1 minute
```

Using `atq` I can verify that the job is actually scheduled. But the job won't start before scheduling another job execution using at. I am wondering if running this inside a container might be the cause. What are your thoughts on this?

If this is actually caused by the execution inside the container, than having supercronic support this case might be valuable.

No source file, test, or entry point is named. Start by reproducing `at -f ./my-script.sh now + 1 minute` inside the container and checking `atq`, then compare it with scheduling a second job; done requires clarifying whether this is a container-specific behavior and defining the expected one-time scheduling support for supercronic.

Written by the indexing model from the issue text.