Prune the “available PRs” list

Hi folks,

We’ve accumulated a fairly long list of “available PRs”, that is,
formatted versions of pull requests that have been closed (either merged
or rejected):

368, 538, 599, 619, 623, 627, 631, 633, 634, 635, 640, 642, 643, 644,
646, 650, 654, 656, 659, 661, 662, 664, 667, 672, 673, 674, 678, 679,
680, 681, 682, 683, 684, 685, 690, 691, 692, 694, 696, 697, 702, 703,
710, 715, 717, 718, 722, 723, 724, 726, 727, 728, 732, 733, 734, 739,
740, 741, 744, 749, 751, 752, 753, 762, 763, 766, 769, 770, 773, 778,
782, 784, 785, 786, 787, 805, and 810

These occupy disk space and (I think) make the publication process run
more slowly. I’d like to prune them all. Are there any that are still
useful?

                                        Be seeing you,
                                          norm

--
Norm Tovey-Walsh
Saxonica