Ruby » Ruby master

revert r50336

• string.c (str_buf_cat): expand later so that the buffer can be
  larger for further use. [Bug #11080] [Bug #11080]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@50386 b2dd03c8-39d4-4d8f-98ff-823fe69b080e