https://bugs.winehq.org/show_bug.cgi?id=37751
--- Comment #11 from Vincent Povirk madewokherd@gmail.com --- All of my testing shows that Mono searches the .exe directory, when loading an assembly referenced by another assembly. This is a slightly different case: Mono is loading an assembly by name. From poking around the code, I'm guessing we'd need mono_install_refonly_preload_hook to change Mono's behavior in this case.
I really need tests for this, and tests need the _AppDomain COM interface working correctly. I'll have to put this on hold until that's fixed in a wine-mono release.