Vim powerline crash

Hi, thanks for this great app.
I have installed powerline for vim with this command:
`pip install powerline-status`

Then select this fond:
```
$ config --show
Droid Sans Mono for Powerline 13.0 pt, background: system foreground: system cursor: system
```

Vim start and display the powerline but a-Shell close/crash when switching to edit mode with « i » key.

This is my .vimrc
```
syntax on
set incsearch
set hlsearch
set lazyredraw
set number
" Configurazione Netrw (browser file di Vim)
let g:netrw_liststyle = 3 " Stile dell'alberatura dei file
let g:netrw_browse_split = 3 " File aperto in un nuovo tab (1 split orrizzontale, 2 split verit
let g:netrw_winsize = 25 " split di 25 caratteri
python3 from powerline.vim import setup as powerline_setup
python3 powerline_setup()
python3 del powerline_setup
set laststatus=2
```