logger.rb: fix extra log ratation
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44203 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
logger.rb: fix extra log ratation
if it has been rotated by another process. based on the patch
by no6v (Nobuhiro IMAI) in [ruby-core:58620]. [Bug #9133]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44203 b2dd03c8-39d4-4d8f-98ff-823fe69b080e