I have a reprepro 5.1.1 installation with the following conf. The idea is to mirror everything locally from Debian Stretch amd64 public mirror.
"distributions":
Origin: debian
Codename: stretch
Description: debian stretch mirror
Architectures: amd64
Components: main contrib non-free
Update: - debian-stretch
Contents: .gz
Log: /var/log/reprepro/debian/stretch.log
SignWith: <key>
Origin: debian
Codename: stretch-updates
Description: debian stretch-updates mirror
Architectures: amd64
Components: main contrib non-free
Update: - debian-stretch-updates
Contents: .gz
Log: /var/log/reprepro/debian/stretch-updates.log
SignWith: <key>
Origin: debian
Codename: stretch-backports
Description: debian stretch-backports mirror
Architectures: amd64
Components: main contrib non-free
Update: - debian-stretch-backports
Contents: .gz
Log: /var/log/reprepro/debian/stretch-backports.log
SignWith: <key>
NotAutomatic: yes
ButAutomaticUpgrades: yes
"updates":
Name: debian-stretch
Method: http://ftp.us.debian.org/debian
Architectures: amd64
Suite: stretch
GetInRelease: no
VerifyRelease: EF0F382A1A7B6500
Name: debian-stretch-updates
Method: http://ftp.us.debian.org/debian
Architectures: amd64
Suite: stretch-updates
GetInRelease: no
VerifyRelease: 7638D0442B90D010
Name: debian-stretch-backports
Method: http://ftp.us.debian.org/debian
Architectures: amd64
Suite: stretch-backports
GetInRelease: no
VerifyRelease: 7638D0442B90D010
The issue is that reprepro does not mirror everything that it finds in http://http.us.debian.org/debian/dists/stretch-backports/main/binary-all/Packages.gz. For example linux-headers-4.16.0-0.bpo.2-common is missing on my local mirror. But it has linux-headers-4.17*.
This also goes for many other packages.
