When inferring foreign keys for a table, the foreign keys of its source table are erased

[XachaB]

Overview

Consider three table: A, B, C
A has some foreign keys, for example, referring to the identifier in C.
B has a foreign key which refers to some column in A (a is the source table).

When doing p.infer() for a package for this database, inside __open_lookup, the foreign keys of A will be erased at this line:

frictionless-py/frictionless/resources/table.py

Lines 250 to 251 in 84c3ea0

	if source_res.schema:
	source_res.schema.foreign_keys = []

I don't understand why: the fact that C refers to A shouldn't mean that A's own foreign keys must be reset ?

I also have the impression that if B referred to itself (with resource being ""), this would erase its own foreign keys relations.