Changing subdir after installation has no effect

[frcl]

I tried to install a plugin, that is in a subdirectory of the repository, but forgot to set the subdir option. When I noticed I had already called minpac#update and after I added the option nothing changed even when I ran minpac#update again. However, removing the package, calling minpac#clean and then installing again made it work. It would be nice if changes in the options also got handled by minpac#update.