* Converts the YAML build mode arrays to objects in special runs
* Adds a dump of the matrix context for each test
This would have made it a LOT easier to debug the build_mode issues...
* Disable the mirror VFD in the -Werror checks
We can re-enable this after we fix the warnings, but I don't want to
conflate code and GitHub changes, so this is a better way to get the
CI to pass for now.
4bbda3038a