Undefined offset notice with context_server_vars

Here is how to reproduce the error :

Create a Server Variables context
Choose a site_banner reaction
Save
Then I get a PHP Notice :

Warning: Illegal offset type in context_condition_map() (line 475 of sites/all/modules/contrib/context/context.module).
Warning: Illegal offset type in context_condition_map() (line 477 of sites/all/modules/contrib/context/context.module).
Warning: Illegal offset type in isset or empty in context_condition_map() (line 474 of sites/all/modules/contrib/context/context.module).