Werk #15639: Predictive Levels: Suppress levels if standard deviation is undefined

This change affects users of the option In relation to standard deviation from Predictive Levels.

Predictive Levels are computed by considering every data point matching the configured reference period. If there is only a single data point available, the standard deviation is undefined. Previously, since the standard deviation was unavailable, Checkmk would use the absolute value of the reference value. In particular, if the reference value was 0, then this would result in a CRIT.

With this Werk, no levels are applied, if the standard deviation is undefined.

To the list of all Werks