Invert condition: we should ignore empty crossrefs rather than non-empty ones for cite key changes. 
Invert condition: we should ignore empty crossrefs rather than non-empty ones for cite key changes. 
ycaihua/skim-app,WoLpH/skim,WoLpH/skim,ycaihua/skim-app,WoLpH/skim,WoLpH/skim,ycaihua/skim-app,WoLpH/skim,ycaihua/skim-app,ycaihua/skim-app