Undefined index notice in wp_reschedule_event()

[SergeyBiryukov]

Previously: #22268

If you have a custom cron schedule defined by a plugin, and a recurring event attached to it, you'll get a notice if the plugin is no longer available:

PHP Notice: Undefined index: minutely in wp-includes/cron.php on line 111

The notice comes from wp_reschedule_event(): tags/3.9.1/src/wp-includes/cron.php#L92​.

In line 110, we should replace redundant 0 == $interval check with isset( $schedules[ $recurrence ] ).

[paulschreiber]

patch with correct indentation

[SergeyBiryukov]

In 29349:

Avoid an undefined index notice in wp_reschedule_event().

props paulschreiber.
fixes #29077.