Fix use of non-existing variable in crashlog.py

[shafik]

Summary

The method find_matching_slice(self) uses uuid_str on one of the paths but the variable does not exist and so this results in a NameError exception if we take that path.

[davide]

LGTM

[aprantl]

Thanks!!

examples/python/crashlog.py

class DarwinImage(symbolication.Image):
                     dwarf_uuid = uuid.UUID(dwarf_uuid_str)
                     if self_uuid == dwarf_uuid:
                         self.resolved_path = self.path
                         self.arch = match.group(2)
                         return True
             if not self.resolved_path:
                 self.unavailable = True
                 print("error\n    error: unable to locate '%s' with UUID %s"
-                      % (self.path, uuid_str))
+                      % (self.path, self.get_normalized_uuid_string()))
                 return False
 
         def locate_module_and_debug_symbols(self):
             # Don't load a module twice...
             if self.resolved:
                 return True
             # Mark this as resolved so we don't keep trying
             self.resolved = True