FillDict: do not use exceptions for flow control

While it's generally better to beg for forgiveness than ask for
permission in Python, it's not a good idea to rely on exceptions to
model control flow, especially if the resulting code is simpler.
Signed-off-by: Santi Raffa <rsanti@google.com>
Reviewed-by: Hrvoje Ribicic <riba@google.com>

lib/objects.py

@@ -75,10 +75,8 @@ def FillDict(defaults_dict, custom_dict, skip_keys=None):
   ret_dict.update(custom_dict)
   if skip_keys:
     for k in skip_keys:
-      try:
+      if k in ret_dict:
         del ret_dict[k]
-      except KeyError:
-        pass
   return ret_dict