Hi,
So the original report experienced this - like me - with emacs.
I could also produce it with just running fc-cache.
Damien's hint is spot-on, thank you Damien!
I had a 2.13 fontconfig-config but 2.12 (lib)fontconfig:
ii fontconfig 2.12.6-0.1
ii fontconfig-config 2.13.0-5
ii libfontconfig1:amd64
2.12.6-0.1 ii libfontconfig1-dev:amd64
2.12.6-0.1
After upgrading everything to 2.13.0-5, the errors are gone.
Would it be an option to require the same (upstream?) version in the
dependency on fontconfig on fontconfig-config. Clearly fontconfig may
break if it get's a too new fontconfig-config.
Best regards
Thomas
