system-packages.txt

# System-installed Python packages to link into our virtualenv.  This
# facility should be reserved for cases where installing them as a normal
# Python dependency is impossible or unreliable (perhaps due to frequent ABI
# changes in system libraries they depend on, or frequent security updates
# managed by the distribution's security team).
#
# The syntax is based on that of PEP 508 requirements, although only
# name-based requirements are permitted, possibly with environment markers,
# and the names are top-level package names rather than distribution names.

# Used by launchpad-buildd.
apt

# Used by Soyuz and other related code to parse Debian packages and
# repository index files, and to compare Debian version numbers.
apt_inst
apt_pkg

# Used by tests to parse sources.list entries.
aptsources

# utilities/js-deps
convoy

# lp.services.fields, lp.services.spriteutils
PIL