Question: discont=FAIL in plot options: bug or feature

What is a bit surpiring,  although the manual doesn't mention it,  the following code produces

the same plots in the 2. and 3. case.  And what about the use of FAIL in similar situations? 

for is_continouos in [true, false, FAIL] do
dc := not is_continouos;
plot(1/x, x=-1..1, discont= dc, thickness=2, color = blue, legend = '1/x')
end do;

Please Wait...