bisect: add example for limiting bisection to specified directories The bisect command does not have an option to limit itself only to subdirectories, but it's possible to use revsets for the --skip option for the same effect. Given the relative obscurity of revsets, it helps to have this as another example for bisect.

subrepo: use posixpath when diffing, for consistent paths This fixes a Windows failure in test-subrepo-recursion.t introduced by c84ef0047a94.

run-tests: fix an unnoticed check-code violation