As I mentioned I find it very odd since t/40_fetch_memberships.t failed whereas t/10_obj_and_params.t, t/20_valid_drupal.t, t/50_term_object_params.t and t/60_membership_object_params.t all passed.

In those test files, the one that fails is the only one that contains:

use open ':std', ':encoding(utf8)';
[download]

Could that be connected to the error ? (Comment it out and see whether the same error arises.)
Does that line *have* to be situated before the loading of Test::Exception ?

Cheers,
Rob