Negative upgrade space left after loading a saved game

[stephengtuggy]

With the latest 0.9.x code, some wonky stuff is going on with regard to ship upgrades and loading saved games.

I am sometimes getting messages like "Space left: -13.5 of 7 cubic meters" whereas, prior to the save point, I had hundreds of cubic meters of upgrade space available.

Issue observed with the code of #821 . But I don't think it's a new issue. I believe it occurs on the main / master branch as well.

This one seems like a high priority to fix, as well.

[BenjamenMeyer]

@stephengtuggy 's description in Chat seems to be related to what I reported in #793 which has been going on for a while. so hopefully we can solve both in one go once we can get to the root of it.