Avogadro libraries provide 3D rendering, visualization, analysis and data processing useful in computational chemistry, molecular modeling, bioinformatics, materials science, and related areas.
It was for QJson (mentioned in the comments in the CMake file). Removing, I will let the buildbot confirm, but worked locally with removal of the CMake lines requiring MoleQueue.
From https://github.com/OpenChemistry/avogadrolibs/blob/master/avogadro/qtplugins/scriptfileformats/CMakeLists.txt
Why should writing an IO script require Molequeue?