@jwrdegoede: What I actually did was to run
# dnf update --enablerepo=updates-testing 'mesa-libGL*' 'libglvnd*'
to check if it resolves the current brokeness related to mesa/libglvnd in current "stable"
[How could this have happened? Does Fedora have any QA?]
# dnf update --refresh --enablerepo=updates-testing 'mesa-lib*' 'libglvnd*'
Package is uninstallable: Error: Transaction check error: file /usr/lib64/libEGL.so.1.0.0 from install of libglvnd-egl-1:0.2.999-7.gitdc16f8c.fc25.x86_64 conflicts with file from package mesa-libEGL-13.0.3-1.fc25.x86_64
@hreindl: With this kernel upgrade you guys are breaking a whole family of chipsets Fedora 23 supported midst of lifetime of a release.
Finally: kernel-4.5.4-200.fc23 seems to work fine on a real Pentium III. So, I believe, the "i686"-probs I am facing, likely are not an i686-architectural issue, but are an i915 driver on i945*/Atom GPUs regression (The machine exposing the breakdowns is an Atom N270 based netbook).
@jforbes: I reported the i915 issue 2 months ago: https://bugzilla.redhat.com/show_bug.cgi?id=1307033 sad but true: it was ignored.
But you are right insofar, it was overshadowed by other issues (those nickc, hjlu and other addressed) which rendered reproducing it difficult.
Anyway, lets stop this discussion here. bodhi is not the right place to discuss it or RH politics.