filters: Do not 500 on non-existing person

Instead 'mock' it with new instance of the class, so the results come
back empty.

Signed-off-by: Arkadiusz Hiler <arkadiusz.hiler@intel.com>
1 job for master in 2 minutes and 7 seconds (queued for 93 minutes and 33 seconds)
Status Job ID Name Coverage
  Test
passed #153637
test

00:02:07