Various checks that are run by fedora-review are broken when the tmpfs mock plugin is enabled, most notably, the "installability" check and "conflicting files" checks fail (because they cannot find "dnf" inside a fresh buildroot). Even when using fedora-review -o "--disable-plugin tmpfs", this happens - so it looks like that mock flag isn't passed to all the necessary places either.

I think given those limitations, fedora-review should probably run all mock commands with --disable-plugin=tmpfs, or something similar to that.