This was previously not covered at all; function
RI_FKey_restrict_del() was not exercised in the tests.
Reviewed-by: Alvaro Herrera <alvherre@2ndquadrant.com>
Reviewed-by: Mi Tar <mmitar@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/7ae17c95-0c99-d420-032a-c271f510112b@2ndquadrant.com/