Reblame at HEAD from dirty lines

HEAD blame seems to be much more useful than index blame. You can
continue following evolution of the line with further jumps while before
you got struck on 'not yet committed' line if it was already added to
the index.

autoload/fugitive.vim

@@ -3895,7 +3895,7 @@ function! s:BlameJump(suffix) abort
   let commit = matchstr(getline('.'),'^\^\=\zs\x\+')
   let suffix = a:suffix
   if commit =~# '^0\+$'
-    let commit = ':0'
+    let commit = 'HEAD'
     let suffix = ''
   endif
   let lnum = matchstr(getline('.'),' \zs\d\+\ze\s\+[([:digit:]]')