Programming error: script direction not yet known

[Jay Anderson]

\version "2.11.49"

\new Staff \relative c''
{
  %\key c \major %Add a key to correct programming errors.
  <<
    { c16 e a g f e d c }
    { s16( s) s-. s-. s( s) s-. s-. }
  >>
}

I didn't find this one in the bug tracker. I'm swapping out the rhythm
on the same passage and this error is created for each staccato:

test.ly:8:15: warning: programming error: script direction not yet known
    { s16( s) s
               -. s-. s( s) s-. s-. }

No slurs are created it seems and the dots are placed strangely.
Adding a key signature fixes the errors.

-----Jay