Ligature to nothing

[Marcos Press]

Hi! I'm full of questions today :D

In these case, I have three times the same last ligature and when I repeat it a fourth time, it doesn't print the same before like you can see at the attached file.

Why?

\version "2.17.28"

c''{e8-. g( e) c( b[) d( b) a8*1/2]( s8*1/2)}
two = \relative c''{e8-. g(-. e)-. c( b[) d(-. b)-. a8*1/2]( s8*1/2)}
three = \relative c''{e8-. g(-. e)-. c(-. b[)-. d(-. b)-. a8*1/2](-. s8*1/2)}
four = \relative c''{e8-. g(-. e-. c-. b[)-. d( b a8*1/2] s8*1/2)}

\score {
  \new Staff {
    \time 4/4
    \one
    \two
    \three
    \four
  }
}

Thanks!

Marcos

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