schedule=asap: Partially completed tasks should have unworked hours starting today

[falkb]

Here we continue the story of #9042.

situation: milestone date set and we have some unscheduled tickets

The ticket must start earlier than today in case we already have worked on it, which means the remaining hours are less than the planned hours. Then you must let it start on 'today minus already worked hours'. Here's illustrated what I mean:

Currently, we have: attachment:ticket:9042:9042_asap_unsched_tick_NOK.jpg​

It should be something like this: attachment:ticket:9042:9042_asap_unsched_tick_OK.jpg​

ChrisNelson already has an idea which way to go: comment:ticket:9042:38