test_imap.rb: fix leaked threads
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@46134 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
test_imap.rb: fix leaked threads
to leak threads.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@46134 b2dd03c8-39d4-4d8f-98ff-823fe69b080e