handle "fugitive:.*" files in s:repl.includes_file

When sending code to the repl from a fugitive :Gd
or :Ge, remove the "fugitive://" prefix, and
"/.git/<rev number>/" path from the buffer name.

This allows for evaluation of code from previous
revisions of a file when inside of a fugitive :Gdiff
or :Gedit window.

plugin/fireplace.vim

@@ -155,6 +155,7 @@ endfunction
 
 function! s:repl.includes_file(file) dict abort
   let file = substitute(a:file, '\C^zipfile:\(.*\)::', '\1/', '')
+  let file = substitute(file, '\C^fugitive:[\/][\/]\(.*\)\.git[\/][\/][^\/]\+[\/]', '\1', '')
   for path in self.path()
     if file[0 : len(path)-1] ==? path
       return 1