It may signal that, as I wrote in the other thread, but only so long as it isn't the de facto standard marriage contract (because everyone has one) and/or it contains clauses to make divorce easier or more-likely. If it contains additional divorce penalties and clarifies inheritence rules for property brought into a marriage, for example, it shows no lack of commitment.

Also, it's not grounds for annulment, but can be used as evidence in an annulment (which usually takes place after a civil divorce).