If I want to avoid accidentally updating something at the wrong time (say, a kernel module which needs a newer kernel) I may place a global exclusion in /etc/yum.conf. However, there doesn't now seem to be a way of deliberately updating this thing without re-editing yum.conf. "yum list" also won't even tell me that a new version of it is available. What I propose is one or more of the following: * an option "--include=xxx" which can override previously specified excludes; * an option "--noexclude" which just ignores all previously specified excludes; * if I name the package exactly on the command line then don't exclude it, despite what the global excludes say (perhaps this should only apply to "yum list"). For now I suppose "yum -c /dev/null" or "yum -c /etc/yum.conf.noexclude" would work, but it's less convenient if you ever actually edit your yum configuration since you then have to keep two files in step with each other.
This isn't something that I really see as a common request. If you really want it, you could easily implement it as a plugin. But it's not something that we're going to do for the yum core.