This argument is implemented in none of the available backends from
dogpile. The only usage is found in own memcache_pool backend but
the flag can be easily replaced by checking tls_context argument.
Change-Id: I8176f427a5906dd68f34a44ee2c200fb76f10220
Signed-off-by: Takashi Kajinami <kajinamit@oss.nttdata.com>
8efb48adf4