I started out planning to pin pikepdf back, but thought to try --prefer-binary before sorting out how to do platfrom specific pinning.

It looks like it is working, I intend to self-merge if this is green.

The appveyor failure is an upload not test failure.

Well, I made the merge rules also apply to admins so I can not.

This file is in the documentation (through dev/dev-requirements.txt); do we want to force this preference on developers? Or just apply it to CI?

I am OK with having this applied for developers too (we are so loose about pinning anyway I think soft-pinning back is OK).

There is motion to make this the default behavior in pip as well.

How would this relate to environment.yml?

It looks like there's a conda-forge feedstock for it: https://github.com/conda-forge/pikepdf-feedstock So we should move to that and then it would definitely be a binary.

Oops, I should have checked the history first; we used to use it, but switched to pip because there were no Windows conda-forge packages, and it seems like there still aren't.

Could one add this switch to the pip-section there? (I could try off course...)