The issue seems to be that object(Thread.Thread) for instance should fall back to 7.8 behavior, which should become object. Its simply handled differently in the 7.9 precompile.
Yes, I thought it was something like that. The reason for the failure is that the 7.8 precompiler behaviour was considered broken.
I have a fix, that enables the old behavior when !api (when its not specified on the command line).
I think that I'd prefer a backport of the api=3 fixes from 7.9, since it's a silent broken success.
After a closer look, it seems easier to just alter the one affected type so that it reads the same way as the 7.8 precompiler parses it. Both precompilers will then agree with a minimum of effort.
Done.
/grubba