Bug#630214: libapt-inst1.2: file conflict with apt 0.8.14.1 (/usr/share/locale/vi/LC_MESSAGES/libapt-inst1.2.mo)

[Jonathan Nieder <jrnieder@gmail.com>]

retitle 630214 libapt-inst1.2: missing Breaks against apt versions from before the split
severity 630214 important
found 630214 apt/0.8.15~exp2
quit

Hi again,

Jonathan Nieder wrote:

> Based on the changelog entry
>
>    * debian/control:
>      - add libapt-pkg4.10 and libapt-inst1.2 library packages
>
> I am guessing there is a missing Breaks+Replaces.

Looking over the debdiff, I see a Replaces now but not a Breaks.  The
Replaces is tracked in Bug#630204 (thanks, Shirish!), so I'll recycle
this bug to track the Breaks.

As mentioned in policy §7.6.1 (Overwriting files in other packages),
a person trying the sequence:

 - unpack new libapt-inst1.2
 - remove new libapt-inst1.2

in the process of recovering from a failing upgrade will find that
/usr/lib/libapt-inst.so.1.2.0 goes missing, and a Breaks is
recommended to avoid that.

On the other hand, with Breaks, a friendly package manager might
update apt first, meaning files are missing in the window between
when new apt is unpacked and libapt-inst1.2 is unpacked.  (This
is _always_ a possibility with Breaks+Replaces, hence probably a
policy bug.)

I suppose my knee-jerk suggestion would be to make libapt-inst1.2
Breaks: apt (pre-split) and Replaces: apt (unversioned), to install
the same files in apt, and to raise a policy bug to fix the advice in
§7.6.1.  Other ideas welcome, too, of course.

Thanks and hope that helps,
Jonathan