collision, is there a workaround?

[Ole Schmidt]

Dear all,

in the third bar on the first beat is a collision in the upper voice  
(between the rest and the bis).
Is this is known issue? Does this have to do with the usage of  
\partcombine? Is there a workaround?
thanks for help

best

ole

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\version "2.11.36"

\layout { ragged-right = ##t }

testfile = \new Staff  {
        
\set Staff.printPartCombineTexts = ##f
        
        \time 6/4
        \clef "G_8"
         \partcombine
        \relative c' {  
                R1.|
                r2
                \times 2/3 { r8 gis'4( } cis,4) r2 |
                \times 2/3 { r8 bis'4( } gis4~ gis fis ~ fis) r4 |
        }
        \relative c' {          
         R1.| r2 r2  r4 b~( | b~ \times 2/3 { b8 cis4~ } cis4 cis e!) r |       

} }

\score {

\testfile

}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%