I upgraded pkg-config from 0.29.2-1 to 1.8.0-10 (debian) and I'm now getting the following diff when running tests:
--- test/blackbox-tests/test-cases/ctypes/github-5561-name-mangle.t
+++ test/blackbox-tests/test-cases/ctypes/github-5561-name-mangle.t.corrected
...
- No package 'fooBar' found
+ Package 'fooBar', required by 'virtual:world', not found
We should postprocess that output in tests or remove it from the output from dune.