[dbapi] move ProgrammingError into cubicweb module
A new ``repoapi`` will be introduced as a replacement for the dbapi. It will
need ProgrammingError too.
Related to #2503918
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))