Ugly collision when acciaccatura is followed by downward stem

[Urs Liska]

I encountered a rather ugly rendering of an acciaccatura.
As you can see in the first attachment the slurs is colliding pretty
hard with the beam.

In addition, it seems that an acciaccatura's slur always crosses the
stem of the following note if that happens to be downwards, see the
second attachment of a more common configuration.

I still don't have a copy of Gould but searching the net for references
seem to indicate that in old editions the slur does *not* cross the
downward stem but stop to the left of it, see for example
http://www.oldflutes.com/articles/kurze/

The original hand-engraving I copied from also does this (see third
attachment), and I'll follow that (last attachment).

The question is: Shouldn't LilyPond do that by default?

Urs

PS: A non-bug question: I tweaked that slur using \shape, but could
someone give me a hint as to use other properties to override, so the
slur doesn't cross the stem but rather goes *to* it?

schwan.png
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schwan.png
Description: PNG image

acciaccatura-durand.png
Description: PNG image

schwan.png
Description: PNG image