Merge latest version (2.48.3-1) with Debian

Status changed to 'Confirmed' because the bug affects multiple users.

Merging/backporting Unison 2.48 to Ubuntu 16.04/14.04 might be required to avoid the issue where newer builds of Unison 2.40 segfault due to a change in the OCaml library (version 4.01.0 -> 4.02.3).

See Ubuntu bug: https://bugs.launchpad.net/ubuntu/+source/unison/+bug/1543374
And Debian bug: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=807019 (thanks to ~linuxien_ref for linking to this on the Ubuntu bug report)

I have 14.04 clients and a 16.04 server and I will be happy to do any needed testing.

Having read through the Debian notes it appears unlikely that 2.40 will ever compile and work against the newer OCaml library in 16.04 LTS. However, 2.48 does fine. There was some question about whether this would work in 14.04 LTS. I have carried out a test using a 14.04 LTS server and a 16.04 LTS client as follows:

Create /etc/apt/preferences.d/unison-ppa to ensure only Unison gets updated from the PPA, as follows:

 Package: *
 Pin: release o=LP-PPA-eugenesan
 Pin-Priority: -1

 Package: unison*
 Pin: release o=LP-PPA-eugenesan
 Pin-Priority: 500

Add the PPA:

 sudo add-apt-repository ppa:eugenesan/ppa

Update the APT cache and update Unison to 2.48:

 sudo apt-get update
 sudo apt-get dist-upgrade

After carrying out this procedure on both 14.04 LTS (AMD64 server) and 16.04 LTS (AMD64 desktop) Unison syncs without any problems. Hopefully this will help others, prove a compatible version can exist between LTS releases and encourage the upgrade of the main Canonical repositories to 2.48?

This bug was fixed in the package unison - 2.48.3-1ubuntu1

---------------
unison (2.48.3-1ubuntu1) xenial; urgency=low

  * Merge from Debian unstable, resolving segfault when transferring files
    between servers (LP: #1421184). Remaining changes:
    - Change default logfile directory to .unison by prepending .unison to
      name of logfile in ubase/trace.ml.

unison (2.48.3-1) unstable; urgency=medium

  * New upstream release (Closes: #705318)
    - remove obsolete patches (fixed upstream)
    - fix debian/generate-manpage.ml
    - thanks to Yuri Kanivetsky for preliminary updating work
    - make temp file names fit within 143 characters (Closes: #504503)
  * Do not use absolute path to icon in desktop file (Closes: #777238)
  * Update debian/copyright
  * Update bash completion installation directory
  * Bump debhelper compat level to 9
  * Bump Standards-Version to 3.9.6

 -- James Page <email address hidden> Fri, 18 Mar 2016 14:51:10 +0000

I can now sync using ssh between two machines running 16.04

Thank you.

Would someone with the appropriate permissions mark this as affecting Ubuntu 14.04 LTS, too? The original bug report remarked on trying to use newer Unison clients with older Ubuntu servers, and in my case, I have the reverse issue - old clients, new server.

For ease of transition as users upgrade their desktops and servers at different times, Unison in 14.04 could be upgraded to 2.48.3-1 with the old package available as 'unison-2.40', akin to the current setup for 'unison2.32.52': http://packages.ubuntu.com/trusty/unison2.32.52

Or, for least disruption to 14.04-only systems where server might not be managed by those with the clients, the opposite would also work, albeit perhaps less ideal - packaging 2.48.3-1 as 'unison2.48.3', leaving 'unison' untouched.

I was trying to sync between computers running Ubuntu 15.10 and a 16.04. I found it was enough to simply copy /usr/bin/unison-gtk to any random directory (eg. ~/Downloads) and run it from there:
chmod 750 unison-gtk
./unison-gtk

A bit ugly, but should allow me to sync between my remaining 14.04 and 15.10 computers as well as the 16.04 one until I get the time to upgrade them all to 16.04.

*I meant copy the /usr/bin/unison-gtk from the 16.04 machine to the 15.10 one

Tim Edwards, there's another way to work-around this that might be easier. I should've added a comment on it.

For the command-line client ONLY: http://packages.ubuntu.com/xenial/unison
For both graphical and command-line client: http://packages.ubuntu.com/xenial/unison-gtk
Make sure to download the right architecture from below, most likely 'amd64' for 64-bit, or 'i386' for 32-bit. You shouldn't need any of the dependencies; Ubuntu 14.04 has new-enough versions.

If you have both packages installed (no need), you'll have to upgrade both or remove the old 'unison' package as 'unison-gtk' seems to offer the same program.

I've had success directly downloading the .deb packages for Unison 2.48.3-1 and installing them on my desktop and laptop running Ubuntu 14.04 with latest updates. Nothing seems to break, just a slight sensible re-arrangement of the GUI buttons. This isn't the best idea, but it's a viable work-around for now. A proper backport to trusty-updates would be better.