Make sure that conflicting dependencies result in a proper error message.
Make sure that conflicting dependencies result in a proper error message.

alexeibs/dub,Flamaros/dub,y12uc231/dub,grogancolin/dub,D-Programming-Language/dub,xentec/dub,nazriel/dub,p0nce/dub,jeanbaptistelab/dub,jelmansouri/dub,schuetzm/dub,Geod24/dub,dreamsxin/dub,Abscissa/dub,Abscissa/dub-data-mod,gedaiu/dub,rjframe/dub