narrow: don't send the changelog information when widening without ellipses When we widen anon-ellipses narrow copy, the server sends the changelog information of all the changesets. The code was copied from ellipses case and in ellipses cases, it's required to send the new changelog data. But in non-ellipses cases, we don't need to send the changelog data as we will have all the changesets locally. Before this patch, there was a overhead of ~8-10 mins on each widening call because of all the changelog information being pulled and being applied. After this patch, we no more pull the changelog information. So this patch can save ~5 mins on Mozilla repo on each widening and more on repos which have more changesets. When we apply an empty changelog from changegroup, there is a devel-warn. This patch kind of hacks to silence that devel-warn. Differential Revision: https://phab.mercurial-scm.org/D4639

changegroup: add functionality to skip adding changelog data to changegroup In narrow extension, when we have a non-ellipses narrow working copy and we extend it, we pull all the changelog data again and the client tries to reapply all that changelog data. While downloading millions of changeset data is still not very expensive but applying them on the client side is very expensive and takes ~10 minutes. These 10 minutes are added to every `hg tracked --addinclude <>` call and extending a narrow copy becomes very slow. This patch adds a new changelog argument to cgpacker.generate() fn. If the changelog argument is set to False, we won't yield the changelog data. We still have to iterate over the deltas returned by _generatechangelog() because that's a generator and builds the data for clstate variable which is required for calculating manifests and filelogs. Differential Revision: https://phab.mercurial-scm.org/D4638