title: scons detecting dependency cycle
body: <p>I have scons picking up a very odd dependency cycle. It goes something like this:</p>
  
  <p>I have an object_file used in some_library which is used by some_executable in directory Fred/Jim and scons fails to buld, saying it has found this dependency cycle:</p>
  
  <p>object_file -> some_library -> some_executable -> Fred/Jim -> Fred -> . -> object_file</p>
  
  <p>for pretty much every object in that library, but not, as far as I can see, for every reference to that library.</p>
  
  <p>More confusingly, we build this for both aix and solaris architectures, and only the solaris build does this, the aix build is fine.</p>
  
  <p>I'm in the middle of migrating our build system, so it's probably something I changed recently, but I'm unsure as to where to look...</p>