Fix tests for append API changes
Fix tests for append API changes

alileza/prometheus,datajet-io/prometheus,keegancsmith/prometheus,prometheus/prometheus,prometheus/prometheus,AlekSi/prometheus,Stackdriver/stackdriver-prometheus,ton31337/prometheus,adamron1/prometheus,dsymonds/prometheus,GoogleCloudPlatform/prometheus,adamron1/prometheus,keegancsmith/prometheus,AlekSi/prometheus,Gouthamve/prometheus,JavierZunzunegui/prometheus,ton31337/prometheus,msiebuhr/prometheus,Gouthamve/prometheus,tattsun/prometheus,tomwilkie/prometheus,amorken/prometheus,gottwald/prometheus,AlekSi/prometheus,ton31337/prometheus,ton31337/prometheus,tomwilkie/prometheus,alileza/prometheus,slok/prometheus,JavierZunzunegui/prometheus,yanghongkjxy/prometheus,agaoglu/prometheus,JavierZunzunegui/prometheus,gottwald/prometheus,GoogleCloudPlatform/prometheus,tomwilkie/prometheus,Colstuwjx/prometheus,datajet-io/prometheus,tattsun/prometheus,sudhi-vm/prometheus,prometheus/prometheus,tattsun/prometheus,eliothedeman/prometheus,tattsun/prometheus,dmilstein/prometheus,GoogleCloudPlatform/prometheus,Stackdriver/stackdriver-prometheus,brancz/prometheus,Conorbro/prometheus,yanghongkjxy/prometheus,Gouthamve/prometheus,prometheus/prometheus,JavierZunzunegui/prometheus,eliothedeman/prometheus,Conorbro/prometheus,sudhi-vm/prometheus,kangwoo/prometheus,sudhi-vm/prometheus,PrFalken/prometheus,datajet-io/prometheus,dmilstein/prometheus,datajet-io/prometheus,PrFalken/prometheus,msiebuhr/prometheus,agaoglu/prometheus,yanghongkjxy/prometheus,amorken/prometheus,brancz/prometheus,dsymonds/prometheus,Colstuwjx/prometheus,Gouthamve/prometheus,slok/prometheus,alileza/prometheus,brancz/prometheus,kzittritsch/prometheus,SaltedMan/prometheus-annotated,brancz/prometheus,yanghongkjxy/prometheus,amorken/prometheus,amorken/prometheus,SaltedMan/prometheus-annotated,AlekSi/prometheus,dsymonds/prometheus,slok/prometheus,keegancsmith/prometheus,Colstuwjx/prometheus,gottwald/prometheus,adamron1/prometheus,Stackdriver/stackdriver-prometheus,adamron1/prometheus,kzittritsch/prometheus,gottwald/prometheus,Stackdriver/stackdriver-prometheus,dmilstein/prometheus,keegancsmith/prometheus,kzittritsch/prometheus,tomwilkie/prometheus,eliothedeman/prometheus,GoogleCloudPlatform/prometheus,eliothedeman/prometheus,PrFalken/prometheus,kangwoo/prometheus,sudhi-vm/prometheus,SaltedMan/prometheus-annotated,SaltedMan/prometheus-annotated,Conorbro/prometheus,PrFalken/prometheus,GoogleCloudPlatform/prometheus,Conorbro/prometheus,msiebuhr/prometheus,dsymonds/prometheus,prometheus/prometheus,alileza/prometheus,alileza/prometheus,msiebuhr/prometheus,kangwoo/prometheus,kzittritsch/prometheus,agaoglu/prometheus,dmilstein/prometheus,agaoglu/prometheus,slok/prometheus,kangwoo/prometheus,keegancsmith/prometheus,Colstuwjx/prometheus