slibtool presently, as exhibited in particular in wrapper Bourne shell scripts produced, does not enclose parameter expansion expressions, e.g. $VARIABLE_NAME, in curly braces. While the presumably underlying assumption that the context they occur within is at all times controlled may appear sensible, this may and indeed has, result in mildly puzzling bugs given e.g. the following - naturally, incorrect - expression:
DL_PATH="$DL_PATH$COLONmetadata-backends/gstreamer/../../.libs"

A tentative patch that addresses this is available at https://www.lucioillanes.de/assets/slibtool%2Balways_enclose_vnames_in_braces.patch.