#390: GTS version fallback

[gmemstr]

Closes #390

[halcy]

:oh_no:

sighs. it's a good PR, thank you, will merge at home when I can run tests, but increasingly I feel trying to use the versions was a mistake, not accounting for everyone who implements the API doing their own thing. I will probably default off it with next version and just offer it for people who want to turn it on to help them debug their problems.