remove REPL.__init__

[JeffBezanson]

Some packages depend on REPL_MODULE_REF being set, which does not work in a compilation process where __init__ methods don't run. It would have been better to use a function like get_repl_if_available(), but here we are.

A related problem is that @doc is exported by Base, but all the code for it is actually in the REPL. I found this interesting use case in RuntimeGeneratedFunctions:

# Duplicate RuntimeGeneratedFunction docs onto @RuntimeGeneratedFunction
@eval @doc $(@doc RuntimeGeneratedFunction) var"@RuntimeGeneratedFunction"

In hindsight, we should have a simple function to get or duplicate a doc string without requiring a lot of REPL code.

[sostock]

Should this be backported to 1.9? It fixes an issue when creating a Docker image on 1.9 (PainterQubits/Unitful.jl#667).

(I realize that 1.10 is around the corner, but there is a backports PR for 1.9.3, so this PR might as well be added to it.)

[maxstb]

I got another issue in OpenSSL.jl which is using the ccall macro as in the Unitful @doc(..) macro PainterQubits/Unitful.jl#667.
Would highly appreciate a fix in 1.9 👍

[vchuravy]

Some packages depend on REPL_MODULE_REF being set, which does not work in a compilation process where init methods don't run. It would have been better to use a function like get_repl_if_available(), but here we are.

With compilation process you mean PackageCompiler? Because the __init__ methods of dependent packages are being run during pkgimg precompilation.