weak deps don't load when prempting `LOAD_PATH`

[t-bltg]

I have a bunch of pushfirst!(LOAD_PATH, "...") in my startup.jl.

This prevents extensions from loading somehow:

julia> using ImageInTerminal
julia> using UnicodePlots
julia> "ImageInTerminalExt" ∈ map(x -> x.name, collect(keys(Base.loaded_modules)))
false

I thought it was fixed by #48352, but it doesn't (this is on julia 1.9.0-beta4 (which has this PR backported)).

How can we debug extensions loading ?

cc @KristofferC.

[t-bltg]

Hum, there seems to be some precompilation related issue here.
Clearing the cache and recompiling seems to fix this.