yum, and 2 packages that provide the same thing

[Stephen Warren]

I have a question re: how yum determines which package to install when
they both provide the same thing.

Specifically, I have:

unison213
  obsoletes:
    unison < 2.27.57-3
  provides:
    unison = 2.13.16-9.fc8.3
    unison213 = 2.13.16-9.fc8.3

unison227:
  obsoletes:
    unison < 2.27.57-3
  provides:
    unison = 2.27.57-7.fc8.3
    unison227 = 2.27.57-7.fc8.3

(Equally, I hit the same issue if unison213 does not provide "unison",
just "unison213".)

If those two packages are in a repository, and I type:

yum install unison

then I *expect* yum to see that both unison213 and unison227 provide
unison, and pick the package that provides the highest version number, and
install it.

However, what actually happens is that yum picks unison213 to install.

I'm not sure if yum is picking:
* The first package it finds
* The "first" package by some sorting order that matches
* Some random package (although it's consistent)

Can anybody shed any light?

Thanks very much.