"MT-safe global config" test needs Internet access
fontconfig 2.14.0 introduces a test — "MT-safe global config" — which requires Internet access, and uses it to silently download a fairly large (16MB) file from a Google server every time the test is run. This won't work at all in a sandboxed build environment, and is wasteful if you have metered Internet access.
The error message in test-suite.log
on failure is also a bit obscure:
Aborting from 'MT-safe global config' with the exit code 6
I think it would be better if this test was disabled by default; ideally there would be some way of pointing it at a local copy of the font files it wants if they are available.