CAS nil error when support_cas=false #154
Description
If ClientError is raised -
https://github.com/evan/memcached/blob/1c659c0d15bcdbd058fff89cc2a696c141011ef4/lib/memcached/memcached.rb#L434
tries variable will be nil, and this line will 💣 https://github.com/evan/memcached/blob/1c659c0d15bcdbd058fff89cc2a696c141011ef4/lib/memcached/memcached.rb#L454
cc @fbogsany