pdf image source path no longer working?

Hello,

is this the right place to report (suspected) bugs?

While upgrading the docbook stylesheets from v1.72.0 to 1.73.1 I
noticed that my custom fo-parameter "img.src.path" stopped working.

My xsl-fo parameter-stylesheet has a line like this:

[...]
 <xsl:param name="img.src.path">../</xsl:param>
[...]

This used to work as expected (find pdf-images one directory level
upwards), but since upgrading to 1.73.1, images in PDFs are now
missing.

thanks,
Claus