Measure_grouping_engraver doesn't sometimes show the conducting signs

[Stefan Thomas]

Dear community,
I have a problem with the Measure_grouping_engraver. 
If the measure is filled with notes everything is ok., but in the case of bar rests or fewer notes not all measure-grouping signs are shown.
For me it would be important, espacially for orchestral parts,  to have all measure-grouping signs displayed.
Is there a way to achieve it (automatically)?

Here is short snippet to illustrate my problem:

\version "2.14.2"
\layout { \context { \Staff \consists Measure_grouping_engraver } }

\score {
  \new Staff \relative c' {
    \compressFullBarRests
#(set-time-signature 7 8 '(4 3)) % compound meter; 7/8 bar, gouped in 4+3
    c8 d e f g f e % this looks nice, as expected
    d2.. % who can I achieve, that both measure groups are shown?
    R2..*2 % same problem as above
    e4 c8 ~c2
  } }