Merge branch 'en/fill-directory-exponential'

The directory traversal code had redundant recursive calls which made its performance characteristics exponential with respect to the depth of the tree, which was corrected. * en/fill-directory-exponential: completion: fix 'git add' on paths under an untracked directory Fix error-prone fill_directory() API; make it only return matches dir: replace double pathspec matching with single in treat_directory() dir: include DIR_KEEP_UNTRACKED_CONTENTS handling in treat_directory() dir: replace exponential algorithm with a linear one dir: refactor treat_directory to clarify control flow dir: fix confusion based on variable tense dir: fix broken comment dir: consolidate treat_path() and treat_one_path() dir: fix simple typo in comment t3000: add more testcases testing a variety of ls-files issues t7063: more thorough status checking