The d2k harvester would suddenly explode if the approaching carryall was
destroyed. This is because there was no distinction between the unit being
carried and the unit being reserved. To test you'll probably have to tweak
the turret missile in weapons.yaml so you can forcefire on the carryall.
* added a bool to check if carryall is actually holding it's target
* fixed harvester being stuck in reserved mode
804cdee8f0