Well now. I even have replicated how I wound up going down that primrose path. When I went back to my production code, I found in my inheriting module; after applying the revelation I talked out in this forum:

use base qw (Config::General::Extended);
sub new {
...
  my $self = new SUPER::new (
...
[download]

Which of course executes C::G::Extended->new... and that's a bad thing.

Instead of changing SUPER to Config::General, as I should have, I changed the use base line. Ah. So that's what happened.