lconvert input file ordering confusion

Situation: combining .qm files into one .qm file

qt_es.qm contains "dependency catalog" entries only,

whereas qt_pt_PT.qm contains a lot of translated texts.

So, we need to combine qtbase_es (and friends) AND qt_es, to get a combined qm file for each language.

If you call lconvert with qt_es first, like:

lconvert -i qt_es.qm qtbase_es.qm

The "dependency catalog" entries remain in the output file, and will not load if those subfiles are not distributed to the user.

If you reorder the call, ie

lconvert -i qtbase_es.qm qt_es.qm

Then the dependency-catalog lines are NOT included, and the translation file will successfully load.

This is very confusing, as the reason for refusing to load the translation is not obvious, and required tracing through the sourcecode to discover it was failing when it couldn't find the qtbase_es.qm file