Fixing bug with inner compare loop.

src/bignum_helper.cpp

@@ -134,7 +134,7 @@ namespace math { namespace detail {
       do {
         subtract_nounderflow(remainder, value, shift);
         add(accum, powers[ipow], shift);
-      } while (compare(remainder, value) >= 0); // Up to 9 times
+      } while (compare(remainder, value, shift) >= 0); // Up to 9 times
     } while (compare(remainder, divisor) >= 0);
     return accum;
   }