Description of problem:
It is possible to create a job pending in "No data available" state, using future execution settings in new job wizard

Version-Release number of selected component (if applicable):
6.13 snap 3

How reproducible:
always

Steps to Reproduce:
1. Define a rex job using a new UI
2. Select future execution
3. In the Future execution step, clear the "Starts at" field. For "Starts before" pick current date from the date picker – in the time field, current time is automatically selected and the input validation correctly shows a warning. Increase the time by one minute.
4. Move to the Review step and wait one minute. When the current time matches the time set in step 3, hit Run

Actual results:
The job is started, remains in no data available status (screen 1)

Expected results:
The job is not run

Additional info:
In step 4 above, if we wait one more minute, the job is not started and "Internal server error" is reported (btw. there could be a nicer message). So it seems that validation upon execution catches current_time > start_before but not current_time = start_before