bad default font on Windows mingw64

[Stephen Leake]

With recent builds of master on mingw64, I'm getting a missing default
font; see attached screenshot of emacs -Q.

When I run my normal startup, something changes, and I a good font. But
then other windows still have bad fonts, such as the ediff control
window. I tried to step thru my normal init (not easy when I can't read
the file!), but I did not find the command that restored the font.

I'm guessing this is related to the recent harfbuzz change? I have not
tried bisect yet.

Any hints on debugging this?
-- 
-- Stephe

Screenshot (10).png
Description: PNG image