Repeat volta not at beginning of piece doesn't get initial repeat bar line

[Patrick or Cynthia Karl]

Section 1.4 of the Notation Manual says about volta repeats:

volta           The repeated music is not written out but enclosed between 
repeat bar lines. If the                             repeat is at the beginning 
of a piece, a repeat bar line is only printed at the end of the                 
             repeat.

But the following snippet does not generate the initial repeat bar line, 
apparently because of the "||" bar line.  But the "||" bar line does not 
indicate the end of a piece.

I have tried several things to get the inital repeat bar line to appear without 
success.  I suspect it's not very difficult.  Can anyone please tell me how to 
do it?  And if I'm correct about the problem being caused by the "||" bar line, 
the documentation should probably be changed.

\version "2.18.2"

music = \relative b' {
    a1 a a a
    \bar "||"

    \break

    \repeat volta 2 { a4 b c d }
}