[Yum] [PATCH] avoid installing 2 copies of everything multilib

[Christopher Allen Wing]

The default behavior of yum when doing an install on a biarch system is to 
install both packages (the main arch and the compatibility arch), e.g. 
running 'yum install libfoo' will install both:

 	libfoo.i386
 	libfoo.x86_64


This is annoying and contrary to, e.g. the way the Red Hat installer 
works. You can override it when installing a single package by explicitly 
asking for the architecture:

 	yum install libfoo.x86_64

instead of

 	yum install libfoo


but there is no way to avoid it, for instance, when doing 'yum 
groupinstall' from a repo with a standard Red Hat comps.xml file.


Here is a patch which adds a new config option 'nomultilibinstall' which 
can disable this:

 	http://www-personal.engin.umich.edu/~wingc/patches/yum/yum-2.2.2-nomulti.patch


This doesn't affect upgrades; when 2 arches of the same package are 
installed, both will be upgraded as usual. It also doesn't prevent a i386 
package from being installed, for instance, if no x86_64 package by that 
name exists. It also doesn't change dependency resolution, so if the i386 
package is actually required by something else, it will still be 
installed.


-Chris Wing
wingc at engin.umich.edu