\score {
\notes \relative c'' { 
	\time 4/4 
% original test case - passes
	r1 << { b4 c d } \\ { a2. } >> r4 << { <b d>4. <b e>4. } \\ { <a c>2  s4 } >> r4 \break
% new test case 1 - fails
	<< 
	{ s2 <dis a'>2 } 
	\\ 
	{ <bes ees ges bes>4 <aes f' aes>8 <bes ges' bes> <b! b'>4. <b b'>8 }
	>> \break
% new test case 2 (swap voices  from case 1)  
	<< 
	{ <bes ees ges bes>4 <aes f' aes>8 <bes ges' bes> <b! b'>4. <b b'>8 } 
	\\ 
	{ s2 <dis a'>2 } 
	>> \break
% new test case 3 (force stems from case 2)
	<< 
	{ \stemDown <bes ees ges bes>4 <aes f' aes>8 <bes ges' bes> <b! b'>4. <b b'>8 } 
	\\ 
	{ \stemUp s2 <dis a'>2 } 
	>> \break
% new test case 4 (try eliminating accidentals in case they interact)
        <<
        { \stemDown <bes ees ges bes>4 <aes f' aes>8 <bes ges' bes> <bes bes'>4. <b b'>8 }
        \\
        { \stemUp s2 <d aes'>2 }
        >> \break


	}
\paper {}

}