Fallback behavior on unparseable conditionals

If firmware offers up an unparseable expression, prcoeed as if the
expression were not there in the first place.  The occurance observed
was not viable.  This hampers the improved error message, but the
firmware will still enforce any rules.

Change-Id: I2be9db12b9fa8da9d40bf6829b3cdc02bbdc946d

pyghmi/ipmi/oem/lenovo/config.py

@@ -116,11 +116,14 @@ class _ExpEngine(object):
 def _eval_conditional(expression, cfg, setting):
     if not expression:
         return False, ()
-    parsed = ast.parse(expression)
-    parsed = parsed.body[0].value
-    evaluator = _ExpEngine(cfg, setting)
-    result = evaluator.process(parsed)
-    return result, evaluator.relatedsettings
+    try:
+        parsed = ast.parse(expression)
+        parsed = parsed.body[0].value
+        evaluator = _ExpEngine(cfg, setting)
+        result = evaluator.process(parsed)
+        return result, evaluator.relatedsettings
+    except SyntaxError:
+        return False, ()
 
 
 class LenovoFirmwareConfig(object):