Use more defensive approach in the switch statement.
Use more defensive approach in the switch statement.

Change-Id: I374fac5f83dae3a63f21b9177223c6175bec7300
Signed-off-by: Piotr Sikora <321b1a11e6b8c7ca12f1b0b438664e52a48b555e@frickle.com>

lilien1010/ngx_cache_purge,FRiCKLE/ngx_cache_purge,ainoya/ngx_cache_purge,FRiCKLE/ngx_cache_purge,lilien1010/ngx_cache_purge,ainoya/ngx_cache_purge