[tryton-debian] Bug#767003: dpkg-maintscript-helper: mv_conffile fails, if new conffile does not exist

[Mathias Behrle]

Package: dpkg
Version: 1.17.13
Severity: important
Tags: patch

Dear Maintainer,

with the package tryton-server I am encountering the following scenario:
- the upstream package does no more include a configuration file for the
  server
- the server now needs an additional logging configuration file

To handle this I took the following steps:
- created the two needed configuration files and installed them to
  /etc/tryton/ (the new configuration directory)
- to keep the the old configuration file (/etc/trytond.conf) for the information
  of the user, I wanted to move it to the new configuration directory
  with
  mv_conffile /etc/trytond.conf /etc/tryton/trytond.conf.pre34

This resulted in an upgrade error:

Entpacken von tryton-server (3.4.0-1) über (3.2.3-1) ...
tryton-server (3.4.0-1) wird eingerichtet ...
Neue Version der Konfigurationsdatei /etc/init.d/tryton-server wird
installiert ...
Neue Version der Konfigurationsdatei /etc/default/tryton-server wird
installiert ...
Preserving user changes to /etc/tryton/trytond.conf.pre34 (renamed from
/etc/trytond.conf)...
mv: der Aufruf von stat für „/etc/tryton/trytond.conf.pre34“ ist nicht
möglich: Datei oder Verzeichnis nicht gefunden
...

The error is caused in finish_mv_conffile, where $NEWCONFFILE is
expected to exist, which is not the case here.

The attached patch solves the problem for me.

Thanks for applying ASAP,
Mathias

-- System Information:
Debian Release: jessie/sid
  APT prefers testing
  APT policy: (990, 'testing'), (500, 'stable'), (400, 'unstable'), (300, 'experimental')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 3.16-2-amd64 (SMP w/4 CPU cores)
Locale: LANG=de_DE.UTF-8, LC_CTYPE=de_DE.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash

Versions of packages dpkg depends on:
ii  libbz2-1.0   1.0.6-7
ii  libc6        2.19-11
ii  liblzma5     5.1.1alpha+20120614-2
ii  libselinux1  2.3-2
ii  tar          1.27.1-2
ii  zlib1g       1:1.2.8.dfsg-2

dpkg recommends no packages.

Versions of packages dpkg suggests:
ii  apt  1.0.9.3

-- no debconf information