[perl #79024] Bleadperl 80ebaca breaks OVID/Class-Trait-0.31.tar.gz
Commit 80ebaca actually exposed an existing bug that Class::Trait was
really close to triggering already:
undef *ISA; # @ISA no longer magical
Class::Trait’s tests just happened not to call ->isa before making any
changes to @ISA.
Now that the meta->isa cache is created immediately,
Class::Trait fails.
This bug can be reproduced in earlier perls by putting an ->isa call
right after the undef:
undef *{"Extra::TSpouse::ISA"};
'Extra::TSpouse'->isa('Class::Trait::Base');
unshift @{"Extra::TSpouse::ISA"}, Class::Trait::Base;
warn Extra::TSpouse->isa('Class::Trait::Base'); # something's wrong
This commit modifies gv_fetchpvn_flags to magicalise @ISA whenever it
is fetched.