`Enum` can't be displayed in REPL

[MarcMush]

trying to show Enum in the REPL throws an error, apparently because it's not a DataType
seems to be broken from 1.3 to 1.5 (I didn't try on master)

(I stumbled across this when trying to see subtypes(Any)

julia> println(Enum)
Enum

julia> Enum isa DataType
false

julia> Enum
Enum Error showing value of type UnionAll:
ERROR: MethodError: no method matching show_datatype(::IOContext{REPL.Terminals.TTYTerminal}, ::Type{Enum})
Closest candidates are:
  show_datatype(::IO, ::DataType) at show.jl:596
Stacktrace:
 [1] show(::IOContext{REPL.Terminals.TTYTerminal}, ::MIME{Symbol("text/plain")}, ::Type{Enum}) at ./Enums.jl:52
 [2] display(::REPL.REPLDisplay{REPL.LineEditREPL}, ::MIME{Symbol("text/plain")}, ::Type{T} where T) at /home/marc/.julia/packages/OhMyREPL/7qVFi/src/output_prompt_overwrite.jl:6
 [3] display(::REPL.REPLDisplay, ::Any) at /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.5/REPL/src/REPL.jl:218
 [4] display(::Any) at ./multimedia.jl:328
 [5] #invokelatest#1 at ./essentials.jl:710 [inlined]
 [6] invokelatest at ./essentials.jl:709 [inlined]
 [7] print_response(::IO, ::Any, ::Bool, ::Bool, ::Any) at /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.5/REPL/src/REPL.jl:238
 [8] print_response(::REPL.AbstractREPL, ::Any, ::Bool, ::Bool) at /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.5/REPL/src/REPL.jl:223
 [9] (::REPL.var"#do_respond#54"{Bool,Bool,REPL.var"#64#73"{REPL.LineEditREPL,REPL.REPLHistoryProvider},REPL.LineEditREPL,REPL.LineEdit.Prompt})(::Any, ::Any, ::Any) at /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.5/REPL/src/REPL.jl:822
 [10] #invokelatest#1 at ./essentials.jl:710 [inlined]
 [11] invokelatest at ./essentials.jl:709 [inlined]
 [12] run_interface(::REPL.Terminals.TextTerminal, ::REPL.LineEdit.ModalInterface, ::REPL.LineEdit.MIState) at /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.5/REPL/src/LineEdit.jl:2355
 [13] run_frontend(::REPL.LineEditREPL, ::REPL.REPLBackendRef) at /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.5/REPL/src/REPL.jl:1143
 [14] (::REPL.var"#38#42"{REPL.LineEditREPL,REPL.REPLBackendRef})() at ./task.jl:356

julia> versioninfo()
Julia Version 1.5.0
Commit 96786e22cc (2020-08-01 23:44 UTC)
Platform Info:
  OS: Linux (x86_64-pc-linux-gnu)
  CPU: Intel(R) Core(TM) i7-7700K CPU @ 4.20GHz
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-9.0.1 (ORCJIT, skylake)