io.c: truncate before appending
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@46372 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
io.c: truncate before appending
instead of truncating before reading.
[ruby-core:55951] [Bug #8625]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@46372 b2dd03c8-39d4-4d8f-98ff-823fe69b080e