[CentOS] rpm -U query

CentOS, RHEL, all versions.

Suppose I am upgrading a package foo-1.0 to foo-2.0 (assume foo is not relocatable), and both packages have %preun sections in their .spec files. It appears that foo-1.0's %preun is run after foo-2.0 has been installed. So what happens if foo-1.0 needs to run a binary that was provided as part of foo-1.0 during its %preun stage, and a binary of the same name is provided with foo-2.0? The installed binary is now foo-2.0's, right? So how to run foo-1.0's binaries during its %preun stage? Is the old binary available under a different name before it gets erased?

-steve