title: Why does my rdebug session say "*** No sourcefile available"
body: <p>I'm not sure what the pattern of behaviour is but some programs - notably simple rack.ru based ones running in thin - can't easily be debugged. When a breakpoint is tripped, no source is available</p>
  
  <p>Note this isn't the same as this other S.O. [issue][1]</p>
  
  <p>[1]: <a href="https://stackoverflow.com/questions/323010/in-ruby-why-does-my-irb-interactive-debugging-">In ruby, why does my IRB interactive debugging session always say &quot;No sourcefile available&quot;</a> session-always-say-no-sourcefile</p>