Bug#787808: upgrade-reports: actually ledger breaks gnucash

[Anonymous <anonymous@hoi-polloi.org>]

Package: upgrade-reports
Followup-For: Bug #787808

Dear Maintainer,

I am the OP, and just wanted to correct what I said.  After further
investigation, it is the ledger package that breaks gnucash, not the
other way around (ref bug 740757).

The ledger package version should have never advanced.  But now that
the damage is done, the release notes should warn ledger users and it
should suggest that they pin the version to 2.6.x.

-- System Information:
Debian Release: 8.1
  APT prefers stable-updates
  APT policy: (500, 'stable-updates'), (500, 'stable')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 3.16.0-4-amd64 (SMP w/2 CPU cores)
Locale: LANG=en_US.utf8, LC_CTYPE=en_US.utf8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)