[web/test] don't delete uicache directory
Other tests use it, so the rmtree was a bit too much. Set CACHEDIR to a
temporary subdirectory, and only delete that.
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))