Fix file magic

calculate/lib/utils/files.py

@@ -278,11 +278,11 @@ class typeFile:
             r,w = os.pipe()
             devnull = os.open(os.devnull,os.O_WRONLY)
             cat = subprocess.Popen(['/bin/cat',filename],stdout=w,
-                    stderr=devnull)
+                    stderr=devnull,close_fds=True)
             ret = self.magicObject.descriptor(r)
             os.close(w)
             os.close(devnull)
-            cat.poll()
+            cat.wait()
         return ret
 
     def isBinary(self, filename):