Persistent CI failure after OPAM merge

Hi Pierre,

after merging the OPAM MR, CI is failing for master. Rerunning the job several times doesn't seem to make a difference, and even rerunning the entire pipeline didn't fix it.

It seems the doc job is actually rebuilding Prosa from scratch, not using the .vo files from a prior stage. Is that intended? If so, why would it have a dependency and be in the second stage? If it builds everything from scratch, it could just run in the first stage for maximum parallelism.

If you have a chance, could you please take a look at what's going on here?

Thanks, Björn