Show buffer name relative to git folder

autoload/airline/extensions/fugitiveline.vim

@@ -0,0 +1,37 @@
+" MIT License. Copyright (c) 2017 Cimbali.
+" vim: et ts=2 sts=2 sw=2
+
+scriptencoding utf-8
+
+if !exists('*fugitive#head')
+  finish
+endif
+
+
+if exists("+autochdir") && &autochdir == 1
+  let s:fmod = ':p'
+else
+  let s:fmod = ':.'
+endif
+
+function! airline#extensions#fugitiveline#bufname()
+  try
+    let buffer = fugitive#buffer()
+    if buffer.type('blob')
+      return fnamemodify(buffer.repo().translate(buffer.path()), s:fmod)
+    endif
+  catch
+  endtry
+
+  return fnamemodify(bufname('%'), s:fmod)
+endfunction
+
+function! airline#extensions#fugitiveline#init(ext)
+  if exists("+autochdir") && &autochdir == 1
+    " if 'acd' is set, vim-airline uses the path section, so we need to redefine this here as well
+    call airline#parts#define_raw('path', '%<%{airline#extensions#fugitiveline#bufname()}%m')
+  else
+    call airline#parts#define_raw('file', '%<%{airline#extensions#fugitiveline#bufname()}%m')
+  endif
+endfunction
+