Minor bug, git ls-files -o aborts because of broken submodules

$ git init abc $ cd abc $ mkdir def $ echo 'gitdir: blah blah' >def/.git $ git ls-files -o fatal: Not a git repository: def/blah blah

If some directory looks like a submodule but turns out not, that's not a fatal error. The stack trace is something like this. I suspect do_submodule_path should use the gently version..

#1 0x0000000000588a78 in die #2 0x0000000000558ded in read_gitfile_gently #3 0x000000000051e2f6 in do_submodule_path #4 0x000000000051e484 in git_pathdup_submodule #5 0x00000000005340ac in resolve_gitlink_ref_recursive #6 0x00000000005342cf in resolve_gitlink_ref #7 0x00000000004dd20d in treat_directory #8 0x00000000004dd760 in treat_one_path #9 0x00000000004dd971 in treat_path #10 0x00000000004de038 in read_directory_recursive