There is a slight problem when reporting that a dependency with extra is satisfied.
In fact, we only check the "base" dependency.
This can lead to a problem when a dependency is wrongly assumed as present
and the script proceeds to the "next stage" without restarting --
if the next stage tries to use (import) the missing dependency,
the script would crash.
However, that might be a very unlikely set of events and if such case ever happens,
we'll workaround it or fix it.
