There is a pull request for popup.el (emacs-jedi depends on auto-complete.el and auto-complete.el depends on popup.el) to fix this problem: https://github.com/auto-complete/popup-el/pull/28
You might want to watch this pull request. The review process is nearly finished.
For meanwhile, if you don't want to hide popup documentation, you can use pos-tip.el (http://www.emacswiki.org/emacs/pos-tip.el)
Edit:
I think making summary information more compact is a good suggestion. Why not post a feature request in Jedi's issue tracker: https://github.com/davidhalter/jedi