Correct reraising of exception

When an exception was caught and rethrown, it should
call 'raise' without any arguments because it shows
the place where an exception occured initially instead
of place where the exception re-raised

Change-Id: I3ec3680debbfad7c06f2251396e0e8e4e3df6c50

openstackclient/shell.py

@@ -148,10 +148,10 @@ class OpenStackShell(shell.OpenStackShell):
                     'auth_type': self._auth_type,
                 },
             )
-        except (IOError, OSError) as e:
+        except (IOError, OSError):
             self.log.critical("Could not read clouds.yaml configuration file")
             self.print_help_if_requested()
-            raise e
+            raise
 
         if not self.options.debug:
             self.options.debug = None