uneven spacing with uniform-stretching

[Mark Polesky]

Is this a bug?  Turning on the uniform-stretching property
has unexpected consequences.  Except in the first measure of
a system, extra horizontal space is added before the first
beat of a measure if:

1) the measure has only one voice, containing one whole note
2) the measure starts with an accidental
3) the measure marks the beginning of a key change

Probably there are other peculiarities, but this is what
I've observed.

- Mark

* * * * * * * * * *

\version "2.13.21"

\paper {
  ragged-right = ##f
  between-scores-system-spacing = #0
}

stretch = \override Score.SpacingSpanner
            #'uniform-stretching = ##t
space = \markup \pad-around #2 \null

musicA = \relative b' { b1 b b }
musicB = \relative d'' <<
  { d1 d des } \\ { \repeat unfold 12 g,4 }
>>
musicC = \relative d'' <<
  { d1 d \key g \major d } \\ { \repeat unfold 12 g,4 }
>>

{ \musicA }
{ \stretch \musicA }
\space
{ \musicB }
{ \stretch \musicB }
\space
{ \musicC }
{ \stretch \musicC }

uniform-stretching.png
Description: PNG image