Weird behavior/bug for git clean in untracked directory

Hello

I'm a little bit confused about the behavior of git clean when trying to clean multiple files/directories at once. For instance if I create two directories with an empty file in an new git repository as such:

  mkdir tmprepo
  cd tmprepo
  git init
  mkdir a b
  touch a/file b/file

and try to clean both these files at the same time with git clean as such:

  git clean -f a/file b/file

then git will not clean any of the files. However, if I separate the cleaning into two separate calls like this:

  git clean -f a/file
  git clean -f b/file

then both directories will be cleaned. The git clean manual page suggests git clean should support multiple paths/directories:

  SYNOPSIS
         git clean [-d] [-f] [-i] [-n] [-q] [-e <pattern>] [-x | -X] [--] <path>...

  DESCRIPTION
         ...
         If any optional <path>... _arguments_ are given, only those _paths_ are affected.

The expected behavior for me would be that there should be no difference between the first `git clean...' with two files and the two `git clean...' with one file each.

I've tested on the following git versions so far:

  * 2.1.4
  * 2.14.2
  * 2.14.2.959.g6663358d3 (currently latest on next branch)

Best regards, David