title: can't convert Fixnum into String (TypeError)
body: <p>On one pc i am getting this on ruby 1.8.6 and on other pc i am getting error</p>
  
  <pre><code>irb(main):001:0&gt; buff = "12345678"
   =&gt; "12345678"
   irb(main):002:0&gt; buff[4] =0x30
    =&gt; 48
     irb(main):003:0&gt; buff
   =&gt; "12340678"
   irb(main):004:0&gt; @new0 = "123456789"
   =&gt; "123456789"
    irb(main):005:0&gt; @new0[4] = 0x30 
   =&gt; 48
  
  
   &gt; @buff ="123456789"
   =&gt; "123456789" 
    &gt; @buff
   =&gt; "123456789" 
   &gt; @buff[4]= 0x30
   TypeError: can't convert Fixnum into String
  from (irb):3:in `[]='
  from (irb):3
  
    &gt; @buff[4] = 0x30
  </code></pre>