Unit training seems improperly split across barracks

[skjb]

As an example, when attempting to train marines out of 3 barracks, if one of the barracks has a techlab, it seems all commands to train are queued in that barracks first, before commands are split across the other barracks:

When all 3 barracks have no tech lab the training is spread more evenly across all 3.

[dorthrithil]

I experienced the same issue but with multiple Gateways. It seems to be a general multiselect problem, not just specific to upgraded buildings.