merge revision(s) r45534: [Backport #9709]
* string.c (str_buf_cat): should round up the capacity by 4KiB, but not number of rooms. [ruby-core:61886] [Bug #9709]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_1@46187 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
merge revision(s) r45534: [Backport #9709]
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_1@46187 b2dd03c8-39d4-4d8f-98ff-823fe69b080e