xml-commons-apis from Core removes xml-commons-apis12 from Extras,
because the latter contains "Provides: xml-commons-apis = 1.2".
As such, xml-commons-apis upgrades xml-commons-apis12 and removes
it. If you want both packages to coexist, remove the Provides.
For RPM background refer to the current gtkhtml38 thread on
fedora-test-list and the ticket linked therein.
hmm, I really should have known better than that (since I did open a bug about
the same type of situation:
This has now been built into rawhide.