A normal course of action, especially in a test env, might be:
1. yum install ovirt-engine
2. engine-setup
3. work, including 'yum update ovirt-engine-setup' and 'engine-setup'
4. engine-cleanup
5. yum remove ovirt-engine\*
6. go to step 1

Now, if we do not run engine-cleanup, yum remove does not run it for us, but instead backs up the pki directory and removes it. Then, a later yum install followed by 'engine-setup', will find everything intact, except for the pki, and will run a normal "upgrade", except for recreating pki. This will probably leave the system in a partially-working state - with new pki we'll have to reinstall all hosts.

Now, what's the expected/optimal behavior? I can think of at least two opposing views:

1. Drop the pki remove on yum remove. If we do that, then 'engine-setup; yum remove ovirt-engine\*; yum install ovirt-engine; engine-setup' will behave basically as if yum remove/install was not called.

2. (Optionally?) run engine-cleanup, or some variation of it (e.g. with a suitable answer file), on yum remove.

I personally think that (1.) makes more sense. In any case, I think that one of these should be adopted in favor of the current behavior.