Optional local plugins

[blacksails]

I would love to be able to mark a local plugin as optional and simply not load it if it isen't found on the filesystem.

Right now I get an error similar to the following on one of my systems where I don't want this particular plugin to be loaded.

error: failed to install source `~/go/src/github.com/blacksails/my-optional-plugin`
  due to: `/Users/blacksails/go/src/github.com/blacksails/my-optional-plugin` matches 0 directories

I guess the current workaround would be to leverage profiles or create an empty directory at the location.