\skip -- What am I missing?

[Geoff Horton]

I'm obviously not understanding something important about the \skip
command. I'm trying to use it in lyrics to skip over a leading
refrain, and no matter what argument I give it, it skips over exactly
one beat. See the sample below. As I read the documentation, the first
word of verse two ought to appear under the d that begins the third
measure, but it doesn't. It appears under the e in the first measure.
(Verified in 2.6.4 and 2.7.38)

What am I doing wrong?

\include "english.ly"

melody = \relative c'' {
  \key c \major
  c4 c e c | c c c c | d c c c
}

verseOne = \lyricmode {
  re -- frain re -- frain
  re -- frain re -- frain
  verse one verse one
}

verseTwo = \lyricmode {
  \skip 1 \skip 1
  verse two verse two
}

\score {
   \context Staff = main <<
      \context Voice = melody { \melody }
      \context Lyrics = one \lyricsto melody \verseOne
      \context Lyrics = two \lyricsto melody \verseTwo
   >>
}