Membership renewal on Feb 29 of a leap year is calculated incorrectly
Or it doesn't match what the test expects, anyways.
Basically, the membership renewal here in CRM_Member_BAO_MembershipType::getRenewalDatesForMembershipType() will renew a membership that expires on Feb 29 for one year and set the new expiry date to Feb 28. But the test here in CRM_Member_BAO_MembershipTest::testRenewMembership() thinks the membership should expire on Mar 1, which is actually more reasonable.
The problem is the kind of funky add one day and then subtract it later after adding a membership period logic, which doesn't make sense in this case as Feb 29 exists one year, but not the next.