pull-pkg fails to download mixed-component packages

Reproducer:

$ pull-pkg -p bin --distro ubuntu libstrongswan-extra-plugins
Source package lookup failed, trying lookup of binary package libstrongswan-extra-plugins
Using source package 'strongswan' for binary package 'libstrongswan-extra-plugins'
Found strongswan 5.9.1-1ubuntu2 in impish
Pulling only binary package 'libstrongswan-extra-plugins'
Use package name 'strongswan' to pull all binary packages
File libstrongswan-extra-plugins_5.9.1-1ubuntu2_amd64.deb incorrect size, got 0 expected 197088
Download Error: Could not download http://archive.ubuntu.com/ubuntu/pool/main/s/strongswan/libstrongswan-extra-plugins_5.9.1-1ubuntu2_amd64.deb to /tmp/libstrongswan-extra-plugins_5.9.1-1ubuntu2_amd64.deb

It fails because the download URL is wrong: it tries to download from main, while the package is in universe. However the same command works fine with other packages in universe:

$ pull-pkg -p bin --distro ubuntu an
Found an 1.2-6build3 in impish
Using existing file an_1.2-6build3_amd64.deb

This may be happening because src:strongswan has some bin packages in main and others in universe:

$ rmadison -a amd64 -s impish -S strongswan | cut -d'|' -f1,3
 charon-cmd | impish/universe
 charon-systemd | impish/universe
 libcharon-extauth-plugins | impish
 libcharon-extra-plugins | impish/universe
 libstrongswan | impish
 libstrongswan-extra-plugins | impish/universe
 libstrongswan-standard-plugins | impish
 strongswan | impish
 strongswan-charon | impish
 strongswan-libcharon | impish
 strongswan-nm | impish/universe
 strongswan-pki | impish/universe
 strongswan-scepclient | impish/universe
 strongswan-starter | impish
 strongswan-swanctl | impish/universe

This may confuse pull-pkg. I didn't try with pull-lp-debs, but I'd expect it to behave identically, as it's just a convenience script around pull-pkg.