Weird pkg_add -DU bug

[Thomas Klausner <wiz%NetBSD.org@localhost>]

Hi!

I'm currently seeing a weird bug with pkg_add -DU - it installs a
second copy of a package with ".xxxxxx" at the end, but doesn't delete
it when it's done.

This is e.g. triggered by pkgin because that uses -DU for updating
packages, but I can easily reproduce it without pkgin.

With no packages installed, and /usr/sbin/pkg_* deleted to make it
clear which version is used:

(-DU is not necessary in this call, but works)
# PKG_PATH=/packages/All ./work/pkg_install-20201211/add/pkg_add -DU checkperms
# ls /usr/pkg/pkgdb
checkperms-1.12  pkgdb.byfile.db
# PKG_PATH=/packages/All ./work/pkg_install-20201211/add/pkg_add -DU checkperms
# ls /usr/pkg/pkgdb
checkperms-1.12        checkperms-1.12.xxxxxx pkgdb.byfile.db
# PKG_PATH=/packages/All ./work/pkg_install-20201211/add/pkg_add -DU checkperms
pkg_add: package `checkperms-1.12' already has a temporary update directory `/usr/pkg/pkgdb/checkperms-1.12.xxxxxx', remove it manually
pkg_add: 1 package addition failed
#

I went back to 'cvs update -D 20200701' of pkgsrc/pkgtools/pkg_install
and can still reproduce it with that version (20191008). At least one
other person also has seen this.

It seems not everyone does, but I don't understand what makes my
system special.
 Thomas