when using repository config from this package:
Amazon Linux AMI 2015.03 - x86_64
https://download.postgresql.org/pub/repos/yum/9.3/redhat/rhel-6-x86_64/pgdg-ami201503-93-9.3-2.noarch.rpm

i'm getting *.PGDG.rhel7.x86_64 instead of PGDG.rhel6.x86_64

that breaks things as these packages do not exist in:
https://download.postgresql.org/pub/repos/yum/9.3/redhat/rhel-6-x86_64

also if they would some will require systemd

i believe repodata is broken

kind regards

Sebastian