BUG: broken tcl on Python 3.13.0 for Windows

[neutrinoceros]

Hi !
I ran into a crash as I tried upgrading some uv-powered CIs to Python 3.13.0, specifically on Windows.
In short, here's the error message I'm getting

E       _tkinter.TclError: Can't find a usable init.tcl in the following directories: 
E           C:/Users/runneradmin/AppData/Roaming/uv/python/cpython-3.13.0-windows-x86_64-none/lib/tcl8.6 C:/Users/runneradmin/AppData/Roaming/uv/python/lib/tcl8.6 C:/Users/runneradmin/AppData/Roaming/uv/lib/tcl8.6 C:/Users/runneradmin/AppData/Roaming/uv/python/library C:/Users/runneradmin/AppData/Roaming/uv/library C:/Users/runneradmin/AppData/Roaming/uv/tcl8.6.12/library C:/Users/runneradmin/AppData/Roaming/tcl8.6.12/library
E       
E       
E       
E       This probably means that Tcl wasn't installed properly.

See a complete minimal reproducer workflow run at
https://github.com/neutrinoceros/reprod-mpl-win-python-3.13-bug/actions/runs/11267957255/job/31333940631

where I run 6 combos:

• ubuntu-latest + Python 3.13 (from GHA)
• ubuntu-latest + Python 3.13 (from uv)
• windows-latest + Python 3.12 (from GHA)
• windows-latest + Python 3.12 (from uv)
• windows-latest + Python 3.13 (from GHA)
• windows-latest + Python 3.13 (from uv)

and only the last one fails

possibly related to #313

For reference, I do have a workaround for this problem in the real life application I want to test, so this is not necessarily high priority for me, but it seems likely that others might bump into this.

[neutrinoceros]

Actually this might be an upstream issue in CPython itself: python/cpython#125235
It is a bit far from my expertise to tell for sure, but feel free to close this.

[neutrinoceros]

Nevermind, with a bit more work, I'm able to confirm that this has nothing to do with uv managed binaries: the true meaningful difference is the use of a venv.
see https://github.com/neutrinoceros/reprod-mpl-win-python-3.13-bug/actions/runs/11286703705/job/31391493350

Closing in favor of python/cpython#125235