File.open(dir) raises Errno::EACCESS

~| ruby -v
jruby 1.4.0RC1 (ruby 1.8.7 patchlevel 174) (2009-09-30 80c263b) (Java HotSpot(TM) Client VM 1.6.0_16) [i386-java]
~| irb
jruby-1.4.0RC1 > path = '/tmp/foo'; Dir.rmdir(path) if File.directory?(path); Dir.mkdir(path); File.open(path) {}  
Errno::EACCES: Permission denied - Permission denied - /tmp/foo
	from (irb):3:in `initialize'
	from (irb):3:in `open'
	from (irb):3
jruby-1.4.0RC1 >

~| ruby -v
jruby 1.3.1 (ruby 1.8.6p287) (2009-06-15 2fd6c3d) (Java HotSpot(TM) Client VM 1.6.0_16) [i386-java]
~| irb
irb(main):001:0> path = '/tmp/foo'; Dir.rmdir(path) if File.directory?(path); Dir.mkdir(path); File.open(path) {}
Errno::EACCES: Permission denied - Permission denied - /tmp/foo
	from (irb):2:in `open'
	from (irb):2
irb(main):002:0> 

~| ruby -v
ruby 1.8.7 (2009-06-12 patchlevel 174) [i686-linux]
~| irb
irb(main):001:0> path = '/tmp/foo'; Dir.rmdir(path) if File.directory?(path); Dir.mkdir(path); File.open(path) {}
=> nil
irb(main):002:0> 

1.8.7's behaviour is the same as with:
  ruby 1.8.6 (2009-08-04 patchlevel 383) [i686-linux]
  ruby 1.9.1p243 (2009-07-16 revision 24175) [i686-linux]
  ruby 1.9.2dev (2009-07-18 trunk 24186) [i686-linux]