Bug 88457: urls fails to copy&paste in Calc - Asking for directions and code pointers

Hi all,
I was looking at this recent bug:
https://bugs.documentfoundation.org/show_bug.cgi?id=88457&redirected_from=fdo

The bug's behavior is basically: urls from a cell cannot be copied and
pasted in another cell in Calc. IOW nothing happens after pasting (however
special paste seems to work).

It seems the bug was introduced with one of my commits last Summer, namely:
http://cgit.freedesktop.org/libreoffice/core/commit/?h=feature/gsoc14-draw-text-background-color&id=c2580813426a58cd2ab22efacec9d28423201562

This small commit simply registers a new text item, EE_CHAR_BKGCOLOR, to
deal with the background color of text.
Does anyone have a guess of how this could affect this behavior on Calc?

It seems that urls in Calc are automatically filled with a grey background,
so I wonder whether this conflicts with the handling of background color by
EE_CHAR_BKGCOLOR.
Does anyone have some pointers to where this happens in Calc's code (i.e.
where urls are assigned a background)?

Cheers,
Matteo