I Fix this with:

>nano /usr/share/applications/mimeinfo.cache
>edit: inode/directory=baobab.desktop;nemo.desktop; OR inode/directory=audacious.desktop;nemo.desktop;
>with: inode/directory=nemo.desktop;nemo.desktop;

but for new users this can be tricky.

It happens too if you click a device on devices applet, but even if I edit mimeinfo.cache, nothing happens, baobab keeps opening, not Nemo. I already uninstall baobab, too many problems with this bug, but before forget about this bug I tried to see if audacious + cinnamon had this bug too, and it does. I had this bug too on Manjaro with Cinnamon, but I tested manjaro last night and its fixed.

Does manjaro have a source repo with the patched packages?, I've searched and haven't found it (without it I can apply their fix).

Sorry, I've searched and haven't found it too.