Bad symlink should be mv'able by FileUtils

[headius]

Here's the test that fails, from test_fileutils.rb. It's the last 'mv'.

  def test_mv_symlink
    touch 'tmp/cptmp'
    # src==dest (2) symlink and its target
    File.symlink 'cptmp', 'tmp/cptmp_symlink'
    assert_raise(ArgumentError) {
      mv 'tmp/cptmp', 'tmp/cptmp_symlink'
    }
    assert_raise(ArgumentError) {
      mv 'tmp/cptmp_symlink', 'tmp/cptmp'
    }
    # src==dest (3) looped symlink
    File.symlink 'symlink', 'tmp/symlink'
    assert_raise(Errno::ELOOP) {
      mv 'tmp/symlink', 'tmp/symlink'
    }
    # unexist symlink
    File.symlink 'xxx', 'tmp/src'
    assert_nothing_raised {
      mv 'tmp/src', 'tmp/dest'
    }
    assert_equal true, File.symlink?('tmp/dest')
  end if have_symlink?

I'm guessing that somewhere within the guts of FileUtils, it calls methods in JRuby to actually move the file (by recopying it or by doing a filesystem move) and that logic is attempting to canonicalize the path through the bad symlink.

So, this is an interesting and perhaps not too difficult one to fix. Run with jruby test/mri/runner.rb mri/fileutils/test_fileutils.rb.