Assigning lyrics to Devnull results in warnings

[Daniel Johnson]

On 2.10.11, running Documentation/user/lily-d5894a905a.ly results in these
warnings:

lily-d5894a905a.ly:1324:19: warning: Lyric syllable does not have note.
Use \lyricsto or associatedVoice.
lyr = \lyricmode {
                   I like my cat! }
lily-d5894a905a.ly:1324:21: warning: Lyric syllable does not have note.
Use \lyricsto or associatedVoice.
lyr = \lyricmode { I
                     like my cat! }
lily-d5894a905a.ly:1324:26: warning: Lyric syllable does not have note.
Use \lyricsto or associatedVoice.
lyr = \lyricmode { I like
                          my cat! }
lily-d5894a905a.ly:1324:29: warning: Lyric syllable does not have note.
Use \lyricsto or associatedVoice.
lyr = \lyricmode { I like my
                             cat! }

The output is correct, but stderr is littered with warnings.