we have held that this affirmative defense falls within the general requirement of Rule 8(c)(1), the list of enumerated defenses is exemplary rather than exclusive, and the failure to plead this particular affirmative defense results in waiver. See Sayre v. Musicland Grp., Inc., 850 F.2d 350, 354 (8th Cir.1988) (“As with other affirmative defenses, failure to plead mitigation of damages as an affirmative defense results in a waiver of that defense and its exclusion from the case.”). We have also indicated, however, that such a waiver is not absolute and that inclusion of an otherwise-waived issue in a final pre-trial order may, in some cases, preserve or revive the issue for trial. See, e.g., Friedman & Friedman, Ltd. v. Tim McCandless, Inc., 606 F.3d 494, 498-99 (8th Cir.2010) (<HOLDING>). Here, however, the affirmative defense was
holding that inclusion of failure to mitigate damages as an issue in a final pretrial order saved the issue from waiver under rule 8c even though the defendant had failed to plead the issue holding that failure to raise issue in brief constitutes waiver of appeal of the issue holding that the district court properly allowed the defendant who asserted the disputed defense as a contested issue of law in the joint pretrial order to pursue the defense despite the defendants failure to comply with rule 8c holding that partys failure to develop issue in argument section constitutes waiver of issue holding that a partys failure to raise an issue in the opening brief waived the issue even though the party raised the issue in his reply brief