Python & CLI fixes

* 9331: See ticket for an example of an attempt to reproduce. As long
   as bin/omero sessions list still functions normally, this change
   can't really cause any issues, and should hopefully prevent the issue
   in 9331.

* 10361: try `bin/omero admin start --wait=5` etc. (/cc @rleigh-dundee)

* 10346:
    * `brew install zeroc-ice33 && ./build.py`
    * `brew uninstall zeroc-ice33 && brew install ome/alt/ice --python`
    * `dist/bin/omero login` should fail.