Backport 8506 to 2.13
Apt install downloads packages by default using http pipelining. However, apt relies on "Size" field from "Packages" file to match responses, but pulp_deb repos do not appear to have it. In certain condition that causes apt to fail.
root@aptbug:~# curl -sS https://repo.saltproject.io/py3/ubuntu/18.04/amd64/latest/dists/bionic/main/binary-amd64/Packages | grep -c ^Size 14 root@aptbug:~# curl -sS http://foreman.example.com/pulp/deb/MyOrg/Library/custom/Saltstack/ubuntu_18_04_salt_latest/dists/default/all/binary-amd64/Packages | grep -c ^Size 0
More details: https://projects.theforeman.org/issues/32178#note-9