Failed to execute FileUtils.mkdir_p

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From @wilfrem on April 6, 2013 8:4

Hello.

When I executing rubygems,
I find a bug around FileUtils.mkdir_p.

OS: Ubuntu 12.10
C#: mono 3.0.7
$ ruby --version
IronRuby 1.1.3.0 on 3.0.7 (tarball Wed Apr 3 11:21:23 PDT 2013)

When call FileUtils.mkdir_p "/tmp/foo/bar" on condition "/tmp/foo" and "/tmp/foo/bar" not exists, it throws ArgumentError

$ ruby
IronRuby 1.1.3.0 on 3.0.7 (tarball Wed Apr  3 11:21:23 PDT 2013)
Copyright (c) Microsoft Corporation. All rights reserved.

>>> require "fileutils"
=> true
>>> FileUtils.mkdir_p "/tmp/foo/bar"
mscorlib:0:in `GetDirectoryName': Invalid path (ArgumentError)
    from /usr/local/ironruby/bin/../lib/ruby/1.9.1/fileutils.rb:245:in `mkdir'
    from /usr/local/ironruby/bin/../lib/ruby/1.9.1/fileutils.rb:245:in `fu_mkdir'
    from /usr/local/ironruby/bin/../lib/ruby/1.9.1/fileutils.rb:217:in `reverse_each'
    from /usr/local/ironruby/bin/../lib/ruby/1.9.1/fileutils.rb:217:in `mkdir_p'
    from /usr/local/ironruby/bin/../lib/ruby/1.9.1/fileutils.rb:215:in `each'
    from /usr/local/ironruby/bin/../lib/ruby/1.9.1/fileutils.rb:215:in `mkdir_p'
    from /usr/local/ironruby/bin/../lib/ruby/1.9.1/fileutils.rb:201:in `mkdir_p'

I found mkdir_p "/tmp/foo/bar/" call fu_mkdir "", fu_mkdir "" call Dir.mkdir "".
But Dir.mkdir "" throws ArgumentError because it calls GetDirectoryName("") (MRI Ruby throws ENOENT extends SystemCallError)

https://github.com/IronLanguages/main/blob/master/Languages/Ruby/Libraries/Builtins/Dir.cs Line:217

mkdir_p cannot rescue ArgumentError, so it fails. (mkdir_p can rescue SystemCallError, so MRI Ruby can execute it)

Copied from original issue: IronLanguages/main#112