Bug#619275: Perl Policy change to document major version upgrade trigger

[Dominic Hargreaves]

Package: debian-policy
Version: 3.9.1.0

Dear Policy maintainers,

A not-so-recent bug report, #230308, raised the issue of how a long-running
program which would be broken (until restart) by a major Perl package upgrade
(eg from 5.10 to 5.12) could be notified of such a restart. There was a rough
consensus on that bug report that, once triggers were available, they could
be used as means to this end, as proposed on that bug report.

I recently posted a message about this issue to debian-devel
(<20110226190032.GF4803 at urchin.earth.li>) which was met by a resounding
silence. Evidently this isn't a very exciting proposal, but perhaps this
does not mean it is not worth implementing. I would like to enable a
graceful resolution to such problematic situations as spamassassin silently
breaking during a partial upgrade (the topic of the original bug report).

As such, perl 5.12.3-2, currently in experimental, implements the perl
half of this fix, by triggering the perl-major-upgrade trigger if it is
upgraded from a version older than 5.12.0. I've tested this against a
modification of the spamassassin package which implements the receiving
side of the proposal, with success. The implementation is for all
practical purposes identical to the proof of concept posted by Niko to
the original bug.

My proposed modification to the Perl policy is a new section entitled
"Upgrades", attached as a patch against git.

Thanks,
Dominic.

-- 
Dominic Hargreaves | http://www.larted.org.uk/~dom/
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