py3: convert os.readlink() path to native strings on Windows Windows insisted that it needs to be str. I skipped the stuff in the posix module, and left `tests/f` and `run-tests.py` alone for now.

py3: suppress the output from .write() calls in the remaining tests

py3: conditionalize json float precision difference in test-debugcommands.t

py3: byteify extension in test-debugcommands.t

pullreport: rev duplicated and extinct into account If we already have some obsolete and hidden nodes locally and the server send them again to you, it seems useful to point it out instead of being silent about it.

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