As of v3.10 libreswan script verify supports Python3. Please note that for Fedora23 system wide change was accepted by FESCO which implies that all packages on LiveCD must run on Python3. Please change shebang of verify script to use /usr/bin/python3.
Or, if you don't have time for this, I can do it for you.
the ipsec verify routine uses #!/usr/bin/python
why would /usr/bin/python not point to python3?
As upstream, we don't want to hardcode the python version in the shebang
(In reply to Paul Wouters from comment #2)
> why would /usr/bin/python not point to python3?
There happened a lot of discussions about this on Python Fedora channels. For now (and for Fedora 23) /usr/bin/python points to python2 and this might or might not change in the future.
"However, packages in Fedora should not depend on where /usr/bin/python happens to point but instead should call the proper executable for the needed python major version directly, either /usr/bin/python2 or /usr/bin/python3 as appropriate."
> As upstream, we don't want to hardcode the python version in the shebang
As for classical python packages that are installed with setup.py, shebangs are autogenerated with setup.py install. However as this is not the case, you have multiple options considering you don't want to hardcode the python version in the shebang upstream:
1. Develop a mechanism, that would change the shebang line according to what python is present/used at compile/install time (seems overkill)
2. Change it in spec's %prep
Fedora 23 Alpha freeze is approaching (18 days), so I would strongly suggest to go with the spec option and consider developing the mechanism later, if really wanted.