Changelog available here.
Hm? No there's no rebootstrapping here.
- libgit2 and libssh2 won't be linked for a long time, it seems.
- All the --stage 2 stuff is is to compile all the code in the build phase. Without that flag, the build phase builds stage 1 and stage 2 is built in install. Ditto for the check phase.
- All the edits you see in config.toml.in are because they changed some default settings.