Hiding first stem in group hides beam

[TorbjörnBjörkman]

I try to hide the first stem in a beam group and expect this to keep the
beam, just as happens if you hide any other stem in the group. However, the
whole beam goes away.

I run lilypond version 2.18.2 on a Mac.

Code snippet that demonstrates the issue follows. The first two beam groups
show the expected behaviour and the last fails. This seems to be a bug.

Best regards,
Torbjörn Björkman

\score{
  \new Staff 
  \relative c' {
    \cadenzaOn
    c8[ e \once \hide Stem f] 
    c[ \once \hide Stem e f] 
    \once \hide Stem c[ e f] 
  }
}