maintainer-feedback requested: [Bug 263665] ports-mgmt/pkg: attempt to open archive named "(null)"

Bugzilla Automation <bugzilla@FreeBSD.org> has asked freebsd-pkg (Nobody)
<pkg@FreeBSD.org> for maintainer-feedback:
Bug 263665: ports-mgmt/pkg: attempt to open archive named "(null)"
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=263665



--- Description ---
After building some ports with poudriere:

root@monax:/usr/local/poudriere/data/packages/builder-default/All # pkg install
gcc10-10.3.0.pkg 
Updating FreeBSD repository catalogue...
FreeBSD repository is up to date.
All repositories are up to date.
Checking integrity... done (0 conflicting)
The following 1 package(s) will be affected (of 0 checked):

Installed packages to be REINSTALLED:
	gcc10-10.3.0

Number of packages to be reinstalled: 1

Proceed with this action? [y/N]: y
pkg: archive_read_open_filename((null)): Failed to open '(null)'


The same error happens if I use pkg upgrade instead of pkg install.  With a
debugger I see pkg_add_common is being called with path = "(null)".  This comes
from the variable target in pkg_jobs_handle_install.