Checkmk Werk 15172: Interface checks: Fix rare interface mixups

ID: 15172 Title: Interface checks: Fix rare interface mixups Component: Checks & agents Level: 1 Class: Bug fix Version: 2.3.0b1 In rare cases, the interface checks associated multiple interfaces with a given service item. Depending on the exact plugin, this could lead to incorrect monitoring results (wrong data or misleading failures in rate computations). This happened if there was an interface where the combination of alias or description plus index matched the alias or description (without the index) of another interface. For example, the following combination lead to such as mixup: LI: Item: `Ethernet 2` LI: Interface 1: Index 1, Description `Ethernet 2` LI: Interface 2: Index 2, Description `Ethernet` In this case, Checkmk associated both interfaces with the item `Ethernet 2`, resulting in wrong monitoring results. Furthermore, another potential side effect of this issue was that the Perf-O-Meters of affected services crashed with C+: Exception: list index out of range C-: