unpack-trees: heed requests to overwrite ignored files
When a directory exists but has only ignored files within it and we are trying to switch to a branch that has a file where that directory is, the behavior depends upon --[no]-overwrite-ignore. If the user wants to --overwrite-ignore (the default), then we should delete the ignored file and directory and switch to the new branch. The code to handle this in verify_clean_subdirectory() in unpack-trees tried to handle this via paying attention to the exclude_per_dir setting of the internal dir field. This came from commit c81935348b ("Fix switching to a branch with D/F when current branch has file D.", 2007-03-15), which pre-dated 039bc64e88 ("core.excludesfile clean-up", 2007-11-14), and thus did not pay attention to ignore patterns from other relevant files. Change it to use setup_standard_excludes() so that it is also aware of excludes specified in other locations. Signed-off-by: Elijah Newren <newren@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>