pullreport: issue a message about "extinct" pulled changesets Changeset pulled from a remote repository while already obsolete locally can end up hidden after the pull. Hiding obsolete changesets is a good behavior but silently "skipping" some of the pulled content can get confusing. We now detect this situation and emit a message about it. The message is simple and the wording could be improved, however, we focus on the detection here. Evolution is still an experimental feature, so the output is open to changes. In particular, we could point out at the latest successors of the obsolete changesets, however, it can get tricky is there are many of them. So we delay these improvements to another adventure. Another easy improvement would be to merge this message with the previous line about the new nodes and their phases. This is a good example of cases where we can only transmit a limited amount of data to users by default. We need some sort of "transaction journal" we could point the user to.

pullreport: skip or rework some early return We are about to add more logic in this report. Before that, we need it to not quit so early.

pullreport: skip filtered revs instead of obsolete ones Obsolescence is closely related to visibility but still a distinct concept. We can receive changesets that are obsolete but visible (eg: when pulling orphans). Such changeset should be reported too. In addition, the filtering level can be anything, we should respect it.

pullreport: add a test to show misreporting of visible changeset The current code ignores all obsolete changesets including the visible one. We add a test showing this behavior before fixing the behavior.

repo: don't look up context for tip node if it's not needed We were doing repo['tip'].node() or similar in a few places where repo.changelog.tip() would be enough. Differential Revision: https://phab.mercurial-scm.org/D4781

repo: look up nullrev context by revnum, not symbolic name I think lookup of the 'null' symbol should be done via scmutil.revsymbol() and repo['null'] is only supported for historical reasons. However, repo[nullrev] is fine, so we can switch to that instead of switching to scmutil.revsymbol('null'). Differential Revision: https://phab.mercurial-scm.org/D4780

bundle: consistently put revnums in "base" collection The "base" collection contains revnums, except that it can also contain the "null" symbol. That's a little weird. Let's be consistent. Differential Revision: https://phab.mercurial-scm.org/D4779

py3: ensure printing to stdout uses str in test-hgweb-no-request-uri.t

scmutil: accept multiple predecessors in 'replacements' (API) This changeset makes 'cleanupnodes' accepts multiple predecessors as `replacements` keys. The same as it accepts multiple successors as `replacements` values. To avoid breaking all callers, the old and new ways are currently valid at the same time. We'll deprecate and drop the old way later. This change is the first step toward a better tracking of "fold" event in the evolution history. While working on the "rewind" command (in the evolve extension), we realized that first class tracking of folds are necessary. We already have good tracking of splits. When walking the evolution history from predecessors to successors, that makes for a clear distinction between having multiple successors because of the actual splitting of a changeset or content-divergences. The "rewind" command allows restoring older evolution of a stack of changesets. One of its mode walks the evolution history to automatically find appropriate predecessors. This means walking from successors to predecessors. In this case, we need to be able to make the same distinction between an actual fold and other cases. So we will have to track folds explicitly. This changesets only focus on making it possible to express fold at the `cleanupnodes` API level. The actual tracking will be implemented later.

scmutil: expand long "one-liner" When a one-liner gets 3 lines longs, it loses its expressivity benefits. We expand it into a simple for loop. This makes future changes of the code in that area clearer.