Yeah, this is on me now. Hopefully we can just pull in the new sources and they'll be fine, but historically it's taken a couple of days/weeks to get the issues ironed out.

Unfortunately, I'm still on a flaky internet connection (but only for GitHub.com for some reason), so I can't clone the repos I need. But someone else should be able to submit PRs that I can merge:

* clone https://github.com/python/cpython-source-deps/
* disable autocrlf
* checkout tcl, delete all files (except README.md) and extract tcl-8.6.10
* git add --all; git tag tcl-core-8.6.10.0; push and send PR
* checkout tk, delete all files (except README.md) and extract tk-8.6.10
* git add --all; git tag tk-8.6.10.0; push and send PR

Once those are merged:
* checkout cpython repo and update version number in PCbuild/tcltk.props and PCbuild/get_externals.bat
* test build with PCbuild/prepare_tcltk.bat, then build with PCbuild/build.bat
* push, send PR

Before that is merged, I'll branch in cpython-bin-deps so that PRs keep building with the older version, then I can trigger the real build. I'll likely need somebody to download the built files and check them into the cpython-bin-deps repo, but I'll give it a go myself first in case my connection is up to it.

Any volunteers?