One test case has too less solution check

I would like to give some feedback about ...

From: http://www.checkio.org/mission/family-gifts/solve/

[spoiler] find_chains({"Loraine","Leah","Jenifer","Russell","Benjamin","Todd","Maryanne","Penny","Matthew"}, ({"Loraine","Benjamin"},{"Leah","Matthew"},{"Todd","Jenifer"},))

it has actually 7 chain. The testcase test for 6 [['Leah', 'Benjamin', 'Penny', 'Jenifer', 'Matthew', 'Russell', 'Loraine', 'Todd', 'Maryanne'], ['Leah', 'Penny', 'Benjamin', 'Russell', 'Jenifer', 'Loraine', 'Maryanne', 'Matthew', 'Todd'], ['Leah', 'Russell', 'Benjamin', 'Jenifer', 'Maryanne', 'Todd', 'Matthew', 'Loraine', 'Penny'], ['Leah', 'Todd', 'Benjamin', 'Matthew', 'Penny', 'Loraine', 'Russell', 'Maryanne', 'Jenifer'], ['Leah', 'Loraine', 'Matthew', 'Jenifer', 'Benjamin', 'Maryanne', 'Penny', 'Todd', 'Russell'], ['Leah', 'Jenifer', 'Penny', 'Russell', 'Matthew', 'Maryanne', 'Benjamin', 'Todd', 'Loraine'], ['Leah', 'Maryanne', 'Loraine', 'Jenifer', 'Russell', 'Todd', 'Penny', 'Matthew', 'Benjamin']]