Possible appoggiatura slur bug.

[Seng Liang]

Hi, when I typed in a music for violin using Lilypond 2.6.3 for Windows I 
noticed this problem/bug with the appoggiatura slur. Here is the file:

\version "2.6.3" 
\relative { \time 2/4
b'4 b8 b  \appoggiatura ais16 b4.( cis16 d) e8-. d-. cis-. b-. R2 }  

The vertical position of the slur is too low. It is lower than the downward 
stem of the principal note (b4.). While this can be easily fixed by 
\override Slur #'positions I thought I should report this possible bug. It 
appeared on both 2.6.3 and 2.7.12 for Windows. Since I don't have Mac I'm not 
sure if it's fixed in version 2.7.16.
The reason I quote these few bars is because if I just type that particular 
bar, the slur comes out normally.
Thank you.
Seng Liang.