Unable to extend an imported function in a separate cell

[dpsanders]

Doing

import Base: +

struct MyType end

and then

+(x::MyType, y::MyType) = "hello"

in a different cell fails.

[fonsp]

We currently only support the other syntax:

# Don't do the explicit import:
# import Base: +

struct MyType end

Base.(:+)(x::MyType, y::MyType) = "hello"