From: nma@12000.org   
      
   I noticed on some problems, Rubi generates errors when ShowSteps=True,   
   but the error do not show up when ShowSteps=False;   
      
   Here is one example   
      
   ClearAll[A, B, x, a, b, c]   
   ShowSteps = False;   
   Int[((A + B*x)*Sqrt[a + b*x + c*x^2])/x^6, x]   
      
   No error.  Now   
      
   ClearAll[A, B, x, a, b, c]   
   ShowSteps = True;   
   Int[((A + B*x)*Sqrt[a + b*x + c*x^2])/x^6, x]   
      
   And on the third step (i.e. hitting ENTER) these errors are   
   generated   
      
   Recursion depth of 1024 exceeded during evaluation of   
   (If[Head[#1]===Rational,Null,Throw[False]]&)[2]. >>   
   IterationLimit::itlim: "Iteration limit of 4096 exceeded.   
      
   I am using Mathematica 10.1, windows 7.   
      
   I put an example notebook in this folder that contains   
   the above example.   
      
   http://12000.org/tmp/072115/   
      
   --Nasser   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)