@lukevalenty That’s definitely the version string of the current development release that @tansell made a bit over a week ago.
My guess is that apio, or something run by apio, is trying to parse that tinyprog version string to check it and struggling with the “.dev20” suffix on it (perhaps due to the letters or the third dot), in which case, downgrading to the current stable release (1.0.23 if using Python 2; earlier if using Python 3) might fix it. (And releasing 1.0.24 as a stable release, with that version string, might also fix it.)
In theory “pip install” should be defaulting to installing only stable releases, but possibly there are older instructions floating around telling people to explicitly install the dev versions (back when 1.0.22bN was required for features).
pip install tinyprog==1.0.23 --force-reinstall
might be worth trying if that’s the case (ie, dev versions are installed by default, unlike usual pip default).
I believe @tansell is just waiting for someone to say “release 1.0.24 as a stable release”… so that’s the other thing we could try if this is the only 1.0.24 related issue.