In order to use the new versions of GNS3, as the ones present on
Tumbleweed/Factory, it's necessary to have installed python3-certifi for
/usr/bin/gns3server has it as a unspecified dependence.

Follows the error message presented when the package is not present:

Traceback (most recent call last):
  File "/usr/bin/gns3server", line 5, in <module>
    from pkg_resources import load_entry_point
  File "/usr/lib/python3.4/site-packages/pkg_resources.py", line 2880, in
<module>
    working_set = WorkingSet._build_master()
  File "/usr/lib/python3.4/site-packages/pkg_resources.py", line 432, in
_build_master
    ws.require(__requires__)
  File "/usr/lib/python3.4/site-packages/pkg_resources.py", line 741, in
require
    needed = self.resolve(parse_requirements(requirements))
  File "/usr/lib/python3.4/site-packages/pkg_resources.py", line 626, in
resolve
    raise DistributionNotFound(req)
pkg_resources.DistributionNotFound: certifi