@capture_out hangs in Jupyter notebooks

[tkoolen]

@capture_out println(1) appears to hang forever in a Jupyter notebook cell.

[diegozea]

It looks to happen the same with @capture_err

[logankilpatrick]

@suppress does not seem to work in a notebook either. See here:

using VegaLite
using Suppressor
@suppress begin
  α  = rand(10,2)
  β  = rand(10,2)
  v1 = @vlplot(:circle,x=α[:,1],y=α[:,2])
  v2 = @vlplot(mark={"type"=:circle,color="red"},x=β[:,1],y=β[:,2])
  @vlplot()+v1+v2
end

for a re-producible example.