Fix: DateTimePicker passes current seconds as the selected seconds value

[jorgefilipecosta]

Closes: #13898

DateTimePicker does not allow users to pick a value for seconds, so when the user changes a time/date, it should look like a value of 0 was selected as the seconds value. Currently, the seconds of the current date are passed as the selected seconds, which may make it look like a "random" value was selected as the seconds value.

This causes a regression where WP_CRON missed some scheduled posts.

How has this been tested?

I created a new post.
I changed the date/time fields in the post scheduling dialog and I verified with redux dev tools that the editPost action contained a date whose seconds were equal to 0.

[gziolo]

This PR needs to be rebased with master to make Travis green again :)

[jorgefilipecosta]

Hi @gziolo this PR was rebased.

[mapk]

This is great! Thanks for fixing @jorgefilipecosta!

[katsar0v]

Any update on this?

[noisysocks]

This causes a regression where WP_CRON missed some scheduled posts.

Could you elaborate on this? What causes cron to miss the posts?

[katsar0v]

Could you elaborate on this? What causes cron to miss the posts?

I explained it here - #13898 (comment)
But will try again. There are missed schedules (e.g.: https://www.hostinger.com/tutorials/how-to-fix-wordpress-missed-schedule) and there is this famous plugin which fixes it all: https://github.com/sLaNGjI/wp-missed-schedule

Use case: I setup wordpress to use system cron (setup a cronjob calling the wp-cron every minute for example). After setting up the cronjob I plan a post for the next week on 20:00. The time in database stored is 20:00:43 (43 in this case is seconds, fully random, but in fact this are my browser seconds).
Now the cronjob runs every minute and starts on the 0th second. If the cronjob is calling the url via http it might take longer than calling the wp-cron.php via php process (but that's an edge case). When the cron job starts next week on 20:00 the post is not being published, because time is 20:00:01 (time of cron job execution) but the post should be published on 20:00:43 (remember the 43 seconds?).
Now the next time the cron job runs (on 20:01) the post does not get published as well and wordpress says "missed schedule" which really annoys me and probably thousands of other WP users...

[aduth]

Looks good. A nice refactor of some duplicate logic too 👍

[aduth]

Might be nice for some docs, even if there's plenty of prior art of no documentation in this component.