Comment 5 for bug 847353

It must be noted that the problem with donor thread is that it actually doesn't call flush_tables_with_read_lock() (new function in 5.5) from the donor thread, instead it calls reload_acl_and_cache() (which is the 5.1 way). Consequently
1) donor thread must call flush_tables_with_read_lock()
2) reload_acl_and_cache() was wsrep-modified in 5.1. This modification must be reverted since it is no longer used for FTWRL purpose in 5.5.