missing bar numbers after manual line breaks within incomplete measures: bug or feature?

[pls]

Hey all,

according to the NR "bar numbers are typeset by default at the start of every 
line except the first line".  In the following example the second line starts 
with an incomplete measure which automatically results in a missing bar number. 
  I would expect a bar number at the beginning of the next complete measure.  
What's the common practice here?  Gould just generally recommends to "place bar 
numbers at the beginning of each system" but she doesn't say anything about 
lines starting with an incomplete measure.  (I know the commands to make bar 
numbers visible.)

\version "2.17.26"
{
\repeat unfold 4 {c'1} c'2 \bar ""
\break
c'2
\repeat unfold 20 {c'1}
}

tia
patrick