Re: [ITP] unison2.49

[Andrew Schulman <schulman dot andrew at epa dot gov>]

> Andrew Schulman writes:
> > I've built and uploaded packages for the next version of unison, unison2.49.
> > Please add unison2.49 to the package list with me as maintainer.
> 
> Sorry, but why do you need to make the version part of the package name?
> Could you name that package just unison, please?

Sadly, no. The way Unison development works, whenever the developers change
Unison's network protocol in an incompatible way, they bump the second part of
the version number.  So versions of Unison with different second parts of the
version number are incompatible.

For example, all versions 2.48.* can talk to each other, but if you try to use
version 2.48.* to sync with a version 2.49.*, Unison will complain about
incompatible version numbers and quit. 

So the only solution is to make a new package for each incompatible version, so
you can be sure to have whichever version you need to sync to a remote host (and
many different versions are in use in the wild).  At least we use alternatives
to provide a generic symlink /usr/bin/unison.

All of the above is explained in /usr/share/doc/Cygwin/unison*.README.

Years ago it was worse, because any two different versions of Unison were
considered incompatible. So we had to create a new package for each point
release.  I convinced the developers to bump the second part of the version
number only when they made an incompatible change, so at least we could know
that versions x.y.* can all talk to each other.

Andrew