revset: detect integer list on parsing Right now, using "%ld" with `repo.revs("…%ld…", somerevs)` is very inefficient, all items in `somerevs` will be serialized to ascii and then reparsed as integers. If `somerevs` contains just an handful of entry this is fine, however, when you get to thousands or hundreds of thousands of revisions this becomes very slow. To avoid this serialization we need to first detect this situation. The code involved in the whole process is quite complex so we start simple and focus on some "simple" but widespread cases. So far we only detect the situation and don't do anything special about it. The singled out will be serialized in `formatspec` in the same way as before.