takes a tty name to spawn the debug shell on, which allows selecting
a different tty than the built-in default.
+ * Service units gained a new ExecCondition= setting which will run
+ before ExecStartPre= and either continue execution of the unit (for
+ clean exit codes), stop execution without marking the unit failed
+ (for exit codes 1 through 254), or stop execution and fail the unit
+ (for exit code 255 or cases of abnormal termination).
+
…
CHANGES WITH 242: