Invalid redefinition of constant?

I had somehow made a mental note, that is now possible:

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  | | |_| | | | (_| |  |  Version 0.5.2 (2017-05-06 16:34 UTC)
 _/ |\__'_|_|_|\__'_|  |  
|__/                   |  x86_64-linux-gnu

julia> module A
       type A
       x::Int64
       end
       end
ERROR: invalid redefinition of constant A

The module name is bound to the module itself inside the module.