Meta generator should check solution class loaded

[macta]

Due to an iceberg bug, loading a branch might leave out the solution class - generation then skips this file silently and leads to a later Travis failure. Better to fail early on generation.

[bencoman]

Is this random, or do you have a reproducible case? (even if intermittent e.g. only 1 in 10 occurrence)

[macta]

I get it frequently in P7 - but I think its fixed in P8 as I sat with Guille at Pharo days and showed him numerous cases that he was able to capture and subsequently fix.

Moving classes from a tag (like WIP) into a new package was a big catalyst for this bug. As you do more, and solve a few solutions, and load branches and review others, you may see it too.

You can get something a bit different when we create the new packages (as the branch in git has no concept of the baseline to know to load a new package now reference in the baseline). This doesn't cuase the kind of failure I call out here though.