CAS problem with solution

[parisse]

OK, I have found why it does not work: it's sqrt(x^2+2x+1) that is wrongly rewritten as -x-1, there is a missing renormalization of square roots in the series/limit code. You can see it if you do
partfrac(sqrt(x^2+2x+1)-sqrt(x^2))
I'm going to fix that before the end of the week in Xcas.
It was never spotted before because nobody tried limit with the difference of two square roots of perfect squares.