Error entering Pkg mode when loading a "custom" REPL (`"deadlock detected in loading REPLExt -> REPLExt"`)

[KristofferC]

❯ julia +nightly -e 'using REPL' -i -q
(@v1.12) pkg> ┌ Error: Error during loading of extension REPLExt of Pkg, use `Base.retry_load_extensions()` to retry.
│   exception =
│    1-element ExceptionStack:
│    ConcurrencyViolationError("deadlock detected in loading REPLExt -> REPLExt")
│    Stacktrace:
│      [1] start_loading(modkey::Base.PkgId)
│        @ Base ./loading.jl:2036
│      [2] _require(pkg::Base.PkgId, env::Nothing)
│        @ Base ./loading.jl:2399
│      [3] __require_prelocked(uuidkey::Base.PkgId, env::Nothing)
│        @ Base ./loading.jl:2283
│      [4] #invoke_in_world#3
│        @ ./essentials.jl:1079 [inlined]
│      [5] invoke_in_world
│        @ ./essentials.jl:1076 [inlined]
│      [6] _require_prelocked
│        @ ./loading.jl:2274 [inlined]
│      [7] _require_prelocked
│        @ ./loading.jl:2273 [inlined]
│      [8] run_extension_callbacks(extid::Base.ExtensionId)
│        @ Base ./loading.jl:1479
│      [9] run_extension_callbacks(pkgid::Base.PkgId)
│        @ Base ./loading.jl:1514
│     [10] run_package_callbacks(modkey::Base.PkgId)
│        @ Base ./loading.jl:1335
│     [11] _require_search_from_serialized(pkg::Base.PkgId, sourcepath::String, build_id::UInt128, stalecheck::Bool; reasons::Nothing, DEPOT_PATH::Vector{String})
│        @ Base ./loading.jl:1981
│     [12] _require_search_from_serialized
│        @ ./loading.jl:1891 [inlined]
│     [13] macro expansion
│        @ ./loading.jl:2566 [inlined]
│     [14] macro expansion
│        @ ./lock.jl:273 [inlined]
│     [15] require_stdlib(package_uuidkey::Base.PkgId, ext::String)