context: possibly yield initial fctx in blockdescendants() If initial 'fctx' has changes in line range with respect to its parents, we yield it first. This makes 'followlines(..., descend=True)' consistent with 'descendants()' revset which yields the starting revision. We reuse one iteration of blockancestors() which does exactly what we want. In test-annotate.t, adjust 'startrev' in one case to cover the situation where the starting revision does not touch specified line range.