[Pkg-zsh-devel] Bug#707760: zsh: Alternatives broken for long time during upgrade from zsh4 to zsh5

[Axel Beckert]

Hi Aaron,

Aaron Schrab wrote:
> As far as I can tell, it's just caused by how dpkg works.
> 
> As it's supposed to do, dpkg first unpacked the new version of zsh
> and removed the old version along with doing the same for the other
> packages being upgraded in that run.  Only once that was done did it
> start running the postinst scripts for the packages one by one.
>
> In most cases this isn't much of an issue, most packages will work
> at least somewhat when not configured or when the configuration step
> was done for a previous version of the package.  Here since the
> actual executable moved from /bin/zsh4 to /bin/zsh5 during the
> unpacking phase but update-alternatives wasn't called to do its work
> until the postinst script was run this left the /bin/zsh and
> /usr/bin/zsh links broken during that time.  Once the postinst
> script actually ran, the problem was resolved.

Yep, that came to mind, too, in the meanwhile, but I wasn't sure if
it's just that. So thanks for this -- kind of -- confirmation.

> This would likely be difficult to notice during development.  Since
> in that case it's likely that the zsh package would be upgraded by
> itself rather than with a large number of other packages, in which
> case there wouldn't be much of a gap between when the package is
> unpacked and when the postinst script is run.

Indeed.

A few rough ideas to make this easier for the user:

* Use Pre-Depends in zsh + zsh-common relationship
* Maybe add some hack in the preinst script

		Regards, Axel
-- 
 ,''`.  |  Axel Beckert <abe at debian.org>, http://people.debian.org/~abe/
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