get_hunks error with vim-airline plugin

Problem

After installing the latest version of vim-airline plugin for Vim, opening any file generates the following error:

Error detected while processing function airline#extensions#hunks#get_hunks..<SNR>57_get_hunks..<SNR>57_get_hunks_signify:
line    1:
E117: Unknown function: sy#repo#get_stats
Press ENTER or type command to continue
Error detected while processing function airline#extensions#hunks#get_hunks..<SNR>57_get_hunks..<SNR>57_get_hunks_signify:
line    1:
E15: Invalid expression: sy#repo#get_stats()
Press ENTER or type command to continue
Error detected while processing function airline#extensions#hunks#get_hunks..<SNR>57_get_hunks..<SNR>57_get_hunks_signify:
line    2:
E121: Undefined variable: hunks

Solution

This error is typically caused because one of your other Vim plugins is outdated. Most probably, the vim-signify or vim-gitgutter plugins. Try updating them and see if this error goes away.

If the error still persists, then the hunks feature can be safely disabled by adding this to your .vimrc:

let g:airline_enable_hunks = 0

Tried with: Vim 7.3 and Ubuntu 12.04 LTS