fix: check machine id as some archives are with empty machine-id file (…

…#3747)

Signed-off-by: Chenlizhong <[email protected]>

insights/core/evaluators.py

@@ -155,7 +155,7 @@ def __init__(self, broker=None, system_id=None, stream=sys.stdout, incremental=F
 
     def observer(self, comp, broker):
         super(InsightsEvaluator, self).observer(comp, broker)
-        if self.system_id is None and Specs.machine_id in broker:
+        if self.system_id is None and Specs.machine_id in broker and broker[Specs.machine_id].content:
             self.system_id = broker[Specs.machine_id].content[0].strip()
 
         if self.release is None and Specs.redhat_release in broker and broker[Specs.redhat_release].content: