Consider:

const X = 1
workspace()
const X = []

On master, putting this in a file and running it results in an error (ERROR: LoadError: invalid redefinition of constant X), although pasting it into the REPL works. It works in both cases on 0.6.

This functionality was useful for package tests, but the docs do say that "This function should only be used interactively." However, I can also make it fail at the REPL if that is desired:

julia> const X = 1; workspace(); const X = []
ERROR: invalid redefinition of constant X