Why does \skip extend an extender

[Patrick or Cynthia Karl]

In the following snippet:

music = \relative b' {
        c4 d e f
        f g a b
        c,1
}

Lyrics = \lyricmode {
        c d e __ _
        _ \skip 1 \skip 1 \skip 1
        C
}

\score {        
        \new Staff \music
                \addlyrics \Lyrics
        \layout { }
}
        
I want the three skips to skip past the notes "g a b".  That is, I want the 
singing of “e” to terminate with the 2nd “f”.  But for some reason the extender 
is extended through the notes “g a b”.  How can I fix this?