Description of problem:
I installed gajim through dnf and then used the built-in plugin manager to install the omemo plugin. Apparently this plugin depends on the axolotl python library which is not available in fedora (as far as I can see).
When trying to install the OMEMO plugin, the installation doesn't seem to go through (the plugin doesn't appear in the list of installed plugins) but there was no error message and gajim continues to work correctly.
After quitting gajim, it won't start anymore because of the missing dependency.

Version-Release number of selected component (if applicable):
0.16.5-3

How reproducible: reproducible


Steps to Reproduce:
1. Start gajim
2. Click on Edit > Plugins
3. Click on tab Available
4. Check the box next to OMEMO and click "Install/Upgrade"
5. Once the installation completes, quite gajim (note: it's not enough to close the roster windows) and try to restart it.

Actual results:
Gajim doesn't start

Expected results:
Gajim starts

Additional info:
If I try to start it from a terminal, it gives me the following traceback (which is how I discovered what was the missing dependency):

Traceback (most recent call last):
  File "gajim.py", line 533, in <module>
    interface.run()
  File "/usr/share/gajim/src/gui_interface.py", line 2733, in run
    gajim.plugin_manager = plugins.PluginManager()
  File "/usr/share/gajim/src/plugins/helpers.py", line 129, in __call__
    cls.instance=super(Singleton, cls).__call__(*args,**kw)
  File "/usr/share/gajim/src/plugins/pluginmanager.py", line 104, in __init__
    pc = PluginManager.scan_dir_for_plugins(path)
  File "/usr/share/gajim/src/plugins/helpers.py", line 114, in wrapper
    result = f(*args, **kwargs)
  File "/usr/share/gajim/src/plugins/pluginmanager.py", line 476, in scan_dir_for_plugins
    if not issubclass(module_attr, GajimPlugin) or \
  File "/usr/share/gajim/src/common/demandimport.py", line 86, in __getattribute__
    self._load()
  File "/usr/share/gajim/src/common/demandimport.py", line 58, in _load
    mod = _origimport(head, globals, locals)
ImportError: No module named axolotl