The integrate_hypertangent result was coming from the

```
In [3]: DE4 = DifferentialExtension(extension={'D':[Poly(1, x), Poly(1/x, t1), Poly((t2**2 + 1)/x, t2)], 'Tfuncs':[log, Lambda(x, tan(log(x)))], 'L_K':[1], 'L_args':[x], 'E_K':[], 'E_args':[], 'T_K':[2], 'T_args':[t1]})

In [4]: integrate_hypertangent(Poly(t2**2 + 1, t2), Poly(x*t2, t2), DE4)
```

which you should also test in addition to this.