Checkmk Werk 13990: Fix systemd_units check plugin crash on certain initial line characters

ID: 13990 Title: Fix systemd_units check plugin crash on certain initial line characters Component: Checks & agents Level: 1 Class: Bug fix Version: 2.2.0i1 In some cases, the plugin <tt>systemd_units</tt> crashed when parsing raw agent data. In such cases, the Check_MK Discovery service reported "Parsing of section systemd_units failed" and went WARNING. The error message in the corresponding crash report was: C+: IndexError (list index out of range) C-: