Description of problem:
dnf tries to remove installonly packages over installonly_limit during a completely irrelevant transaction.

Version-Release number of selected component (if applicable):
dnf-0.6.4-2.fc22.noarch

How reproducible:
always

Steps to Reproduce:
1. install more than 3 versions of kernel (or set installonly_limit to one less than number of your installed kernels)
2. dnf update dnf

Actual results:
# dnf update dnf
Using metadata from Thu Mar 19 01:12:46 2015
Dependencies resolved.
==========================================================================================================
 Package                     Arch                Version                       Repository            Size
==========================================================================================================
Removing:
 kernel                      x86_64              3.17.4-301.fc21               @System                0  
 kernel-core                 x86_64              3.17.4-301.fc21               @System               40 M
 kernel-modules              x86_64              3.17.4-301.fc21               @System               17 M

Transaction Summary
==========================================================================================================
Remove  3 Packages

Installed size: 57 M
Is this ok [y/N]: 


Expected results:
# dnf update dnf
Using metadata from Thu Mar 19 01:12:46 2015
Error: No packages marked for upgrade.


Additional info:
The same behaviour observed for clean_requirements_on_remove set to both true and false.
At least clean_requirements_on_remove=false shouldn't do it.