Partial loads not taken from storage even when permitted

Issue description

Partial loads not taken from storage even when permitted.

I've re-enabled partial loads in update 2. Not sure if this ever worked right. Used an update 1 game.

Reproduction steps

Have mine fill up a bin with dirt.

Change dirt bin to fully empty with red slider to zero.

Create a mine control tower, set bin to export from bin. Set an area to dump. Set export to a disabled dirt bin somewhere else, so they dump locally.

Game version and build number

v0.6.0a b315

Operating system

Windows

Partial does not apply to dumping from storage silos. One of the reasons is that there is nothing to gain by doing this in partial, unlike when balancing cargo between machines, for instance.