[server/rql2sql] use VariableRef.is_equivalent explicitly instead of relying on __eq__
What we want to compare is the variable referenced by the VariableRef,
we should make that explicit.
Closes #6694406
import ConfigParser
try:
undo_actions = config.cfgfile_parser.get('MAIN', 'undo-support', False)
except ConfigParser.NoOptionError:
pass # this conf. file was probably already migrated
else:
config.global_set_option('undo-enabled', bool(undo_actions))