Plugins and recompilation of modules

I discovered that when a plugin is enabled, ghc will rebuild all modules even if only the top level module changed.

I created a minimal example to reproduce this issue, see the repo.

If I compile both modules: A and B, then I modify the top level one (B) and then recompiles again what GHC will do depends whether the plugin is enabled or not. In the first case it only recompiles the modified module, in the other case it will recompile both modules. I checked that for the defaultPlugin with pluginRecompile set to either of the two: purePlugin and flagRecompile.

This might be a regression since the tickets #7414 (closed) and #12567 (closed) are both closed.