I have a server running Debian Stretch that I need to install PHP 7.1 on, which isn't available in the default repositories of Stretch, but in Testing aka Buster. I tried to use apt pinning to add the Buster repositories with a lower priority, so packages from Buster only get installed when I specify them.
I added the following to the (otherwise untouched) /etc/apt/sources.list:
# buster to get php 7.1 for nextcloud
deb http://ftp.de.debian.org/debian/ testing main
deb-src http://ftp.de.debian.org/debian/ testing main
deb http://security.debian.org/debian-security testing/updates main
deb-src http://security.debian.org/debian-security testing/updates main
And I created a file called 01-buster in the (otherwise empty) /etc/apt/preferences.d directory, with the following content:
Package: *
Pin: release a=stable
Pin-Priority: 700
Package: *
Pin: release a=testing
Pin-Priority: 650
Now, when I run apt update, I get the following output:
Hit:1 http://security.debian.org/debian-security stretch/updates InRelease
Ign:2 http://ftp.de.debian.org/debian stretch InRelease
Hit:3 http://security.debian.org/debian-security testing/updates InRelease
Hit:4 http://ftp.de.debian.org/debian testing InRelease
Hit:5 http://ftp.de.debian.org/debian stretch-updates InRelease
Hit:6 http://ftp.de.debian.org/debian stretch Release
Reading package lists... Done
E: Invalid record in the preferences file /etc/apt/preferences.d/01-buster, no Package header
Other commands, such as apt search php or apt policy return the same error.
I am 95% sure I have done apt pinning in the past successfully with exactly the same settings. Does anyone have an idea what is going on here?
