Problem with xsl transformation

[Regina Henschel]

Hi all,

the helpauthoring.oxt uses the filter xmlhelp2soffice.xsl for import and 
soffice2xmlhelp.xsl for export. The problem is, that for a special input 
the export filter works in

Version: 5.1.0.0.alpha1+
Build ID: fdafa5302df26df4f147b0d2efb6064389a1330c
TinderBox: Win-x86 at 62-merge-TDF, Branch:MASTER, Time: 2015-08-22_23:42:26

but no longer works in

Version: 5.1.0.0.alpha1+
Build ID: eb2e1ab4651350bffc53f618961a910bd3bbcfd9
TinderBox: Linux-rpm_deb-x86_64 at 70-TDF, Branch:master, Time: 
2015-09-02_23:57:52

The xml export result is not even well-formed now.

Can someone give me a hint, what might have been changed between 
2015-08-22 and 2015-09-02 in regard to xsl transformation?

I do not think, that the error is in the .xsl itself, nevertheless here 
are the references:
The related bug is tdf#94154.
The packed extension is in http://dev-www.libreoffice.org/helpauthoring/
The source is in 
http://cgit.freedesktop.org/libreoffice/contrib/dev-tools/tree/helpauthoring

Kind regards
Regina