Fedora 22 Workstation did not install python 2 by default. Updated samba packages now require python 2. This is a regression.
Can you show what exactly is pulling python2 in? Samba has python bindings which support python2 only and are used by FreeIPA server to provide interoperability with Active Directory, thus freeipa-server-trust-ad subpackage depends on samba-python which is currently only supports python2. If you installed samba-python subpackage, it is indeed forcing use of python2. There is currently no solution to this, work to support python3 is still being done upstream. So can you provide more details of 'regression'?
Their seems to be new dependencies with the samba-4.3.1-3 that samba-4.3.0-0.1.rc4 did not have. samba-common-tools = 2:4.3.1-3.fc23 is needed by samba-common-2:4.3.1-3.fc23.noarch samba-libs = 2:4.3.1-3.fc23 is needed by samba-common-tools-2:4.3.1-3.fc23.x86_64 libpython2.7.so.1.0()(64bit) is needed by samba-libs-2:4.3.1-3.fc23.x86_64 If fedora is moving away from python2 and workstation did not install python2 by default but now requires it for updates this is a regression.
The first two are proper dependencies, they were required to fix some other bugs. The third one, I think, can be moved out to samba-python. It is needed for internal Samba's python integration for the 'make test' and WAF modules and can easily go into samba-python. At least, there is no direct dependency to it other than from WAF and make test.