[server] Add missing indices for undo support (closes #3259691)
The tables used by the 'undo' feature were missing some indices, which
among other things triggered repeated sequential scans when deleting old
transactions.
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))