logger.rb: fix r43511 for Windows
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@43513 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
logger.rb: fix r43511 for Windows
open file can't be removed or renamed on Windows. [ruby-dev:47790]
[Bug #9046]
fork.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@43513 b2dd03c8-39d4-4d8f-98ff-823fe69b080e