(In reply to comment #1)
> Can you bisect Mesa?

I can, but (this sounds almost shameful to admit) I can't find which commit
marks the 10.1.4 release. I bisected it at the commit
03a0471832a9d336741bca194873e8c8185245fe (it talks about adding a news item
related to 10.4.1), but running LD_LIBRARY_PATH="./src/glx"
LIBGL_DRIVERS_PATH="./lib/gallium/" mpv <file-name> gave me the same error.

If you can give me the requisite commit, I will bisect it at the proper place
and then try this again. Not being a coder, or even someone who uses git
regularly, I apologise if this is too basic a question to be asked.