client: allow non-abs paths when splitting keybase paths
client: allow non-abs paths when splitting keybase paths

Suggested by songgao.

Issue: #15044

keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client