redirector: check for .kbfs_error as a double-check
redirector: check for .kbfs_error as a double-check

Issue: KBFS-2774

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