I feel you should have a separate block if the `glob` finds multiple `jellyfish-` directories, because in that case there's clearly something going on that we do not expect.

Suggestion:

```python
jellyfishdirs = glob.glob(os.path.join(os.path.dirname(self.cfg['start_dir']), "jellyfish-*"))
if len(jellyfishdirs) == 1 and os.path.isdir(jellyfishdirs[0]):
...
elif jellyfishdirs:
    self.log.error("Found multiple 'jellyfish-*' directories: %s" % jellyfishdirs)
else:
    self.log.info("no seperate source found for jellyfish, using shipped version")
```