[dataimport] _create_copyfrom_buffer: put converters into a list
Cleans up the code to avoid a succession of ifs.
Related to #3845572
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))