The following snippet:
\version "2.9.26"
\score {
\context Score <<
\new Staff <<
\new Voice \relative c'' { \voiceOne c c r c }
\new Voice \relative c'' { \voiceTwo c g r a } >> >>
\layout {}
}
...still produces the following bogus warnings as of 2.9.26:
simultan-rests.ly:8:48: warning: Two simultaneous rest events, junking this one
\new Voice \relative c'' { \voiceTwo c g
r a }
simultan-rests.ly:7:47: warning: Previous rest event here
\new Voice \relative c'' { \voiceOne c c
r c }[1]
I admit these can be useful if one wants to use them to change
all simultaneous rests in one staff to "\oneVoice r \voiceOne"
and "s" respectively, but at least for me they just clutter the
output, and in any case the "junking this one" part is plain
wrong; a correct description in this case would be "keeping
both".