Context fixes

[cchalmers]

My attempt at fixing the context errors, probably introduced by updating tex in d017a3b.

We could just disable the log parsing tests for context. I wonder if anyone other than me has actually used context from this package.

[byorgey]

Interesting, I thought TeX wasn't supposed to change? In any case, if this doesn't work, then sure, we can just disable the log parsing tests if that's the only thing that's failing. I've never used the context stuff; I only use this package indirectly via diagrams-pgf (which I use quite a bit).

[cchalmers]

I thought TeX wasn't supposed to change?

The raw tex and pdftex tests still pass but it looks like context is still changing the interface and format of error messages.

With my local context from nixpkgs (context 2023.05.05) and these changes, it passes everything but UndefinedControlSequence "\\hobx": Unfortunately, the version on CI (looks like 2021) is failing the contextOnline test so you can't get the size of boxes to use as the bounding box in diagrams. But I think it's working again with my version.

I don't fancy debugging the CI version so I'll just comment out all the context tests. If anyone has actually used context with diagrams-pgf and they want this fixed I'd be so surprised I'd probably go and fix it.