Avoid loading error for variants with missing ALT alleles. Fixes chapmanb/bcbio-nextgen#781
Avoid loading error for variants with missing ALT alleles. Fixes chapmanb/bcbio-nextgen#781

arq5x/gemini,udp3f/gemini,udp3f/gemini,bgruening/gemini,udp3f/gemini,bgruening/gemini,heuermh/gemini,bgruening/gemini,bpow/gemini,bw2/gemini,arq5x/gemini,bgruening/gemini,xuzetan/gemini,arq5x/gemini,bw2/gemini,bw2/gemini,xuzetan/gemini,udp3f/gemini,brentp/gemini,arq5x/gemini,heuermh/gemini,bpow/gemini,bpow/gemini,heuermh/gemini,brentp/gemini,heuermh/gemini,xuzetan/gemini,brentp/gemini,bw2/gemini,xuzetan/gemini,bpow/gemini,brentp/gemini