v2.10.0: ls-tree exit status is always 0, this differs from ls(1)

[Steffen Nurpmeso <steffen@xxxxxxxxxx>]

I think this behaviour contradicts the manual which strongly links
ls-tree to ls(1):

  ?0[steffen@wales ]$ ls NEWSS
  ls: cannot access 'NEWSS': No such file or directory
  ?2[steffen@wales ]$ git ls-tree --name-only master NEWSS                                                                                       
  ?0[steffen@wales ]$ ls NEWS                                                                                                                    
  NEWS
  ?0[steffen@wales ]$ git ls-tree --name-only master NEWS                                                                                        
  NEWS
  ?0[steffen@wales ]$ 

Ciao.

--steffen