io.c: not shorten buffer unless succeeded
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@46360 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
io.c: not shorten buffer unless succeeded
read succeeds. [ruby-core:55951] [Bug #8625]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@46360 b2dd03c8-39d4-4d8f-98ff-823fe69b080e