Integral of 1/cos(x) in CAS

[Nigel (UK)]

I have been trying to evaluate the symbolic definite integral
\[\int_{l_1}^{l_2}\!{1\over\cos\theta}\,{\rm d}\theta\]
using the Prime CAS. Using my default setting of no simplification I get a rather complicated but correct answer. My TI-Nspire CAS (which I only switched on to see what it would do with this same integral, honest!) gives a simpler but equivalent result.

This isn't the problem - I understand that there is no good way to define the "simplest" form of an expression, and that different software will give different results. The issue is that using the Prime to simplify the result of the definite integral causes the calculator to hang. Sometimes I can interrupt this; sometimes I can't, and a reset is needed.

Is this a bug? I am using the latest firmware.

Nigel (UK)