bug#22527: 25.0.90; Updating packages seems to be broken

[N. Jackson]

At 18:23 -0400 on Monday 2016-02-01, N. Jackson wrote:
>
> For several years, for my system at least, package update has been as
> simple as:
>
>     M-x list-packages RET
>     U                      ; (package-menu-mark-upgrades)
>     x                      ; (package-menu-execute)
>
> This no longer seems to work. Instead, I get the message:
>
>     Unsigned file ‘org-20160201.tar’ at http://elpa.gnu.org/packages/

This is possibly related to http://debbugs.gnu.org/cgi/bugreport.cgi?bug=22440.

With the new pretest (25.0.92) this problem seems to be fixed. Whether
that means that #22440 is now fixed, or that org is now signed or
something else, I don't know.

> I tried removing the install mark (the `I' in the left margin) for
> org to see if I could get my other packages to update at least, but this
> leads to the message:
>
>     Delete package ‘org-20151123’; and Upgrade these 2 packages 
> (auctex-11.89.1, debbugs-0.9)? (y or n)
>
> This message makes no sense: I don't want to delete org just because I
> can't update it. Naturally I answered `n' to the prompt. But now things
> are stuck in a limbo where I can't update any packages.

This part of my bug report was pilot error. It seems that there has been
a change in behaviour? When package-menu-mark-upgrades marks a package
for upgrade, it now also marks the old version of the package for
deletion. This explains the above message that surprised me. I don't
think it did this before? IIRC, formerly it prompted to delete the old
version after the new version was successfully installed.

If this is a new change in behaviour in Emacs 25, I suppose it should be
in NEWS?