Bug#650601: transition: libpng 1.5

[Tobias Frost <tobi@debian.org>]

Hi Nobuhiro,

Am Mittwoch, den 23.12.2015, 05:29 +0900 schrieb Nobuhiro Iwamatsu:
> Hi Tobias, Gianfranco and Emilio.
> 
> Thanks for your help!
> Sorry, about this transition.
> 
> I don't upload libpng16 with providing libpng-dev now. Because Depend
> of libpng
> is very large and effect for system is large too.
> I was considering to gradually transition in a way that was proposed
> by Michael.
> I just sent a mail about this. Could you check this mail, and
> comment?
> 
> Best regards,
>   Nobuhiro

For me this plan sounds good. 

Some steps couls be parallized thouhg, so for example I think we do not
need to wait libpng to transistion to testing before filing bugs and
making packages ready to compile with (libpng12 and) libpng16.

I think we should also recommend people to B-D on libpng-dev to help
subsequent transistions, maybe in combination with stop providing
libpng-dev when the transistion is completed but having a real package
depending on the latest -dev package. (As Michael pointing out,
Versioned depends are not working with Provided packages.)  
 
(But the release team should give the ok to start)

I'm currently rebuilding all reverse B-Ds (on libpng-dev and libpng12-
dev), but this will still take a few days to complete (currently done
~150packages out of ~450) to sasess the situation -- A summary will be
posted to this bug when ready.

--
tobi