Merge branch 'zh/ls-files-deduplicate'

"git ls-files" can and does show multiple entries when the index is unmerged, which is a source for confusion unless -s/-u option is in use. A new option --deduplicate has been introduced. * zh/ls-files-deduplicate: ls-files.c: add --deduplicate option ls_files.c: consolidate two for loops into one ls_files.c: bugfix for --deleted and --modified