`TypeError: can't pickle _abc_data objects` when a class made with pyfields inherits from an ABC

[smarie]

This happens when @autoclass or @autofields is used with a default value.

It seems that the _abc_data object from the ABC is mistakenly set as a field.

[smarie]

There are two things we can do:

• add an exclude arg to exclude auto-fields by name
• add a check with deepcopy(value) at class creation time and raise an error if this does not work.

[smarie]

This only happens in python 3.7+ by the way