obslog: make {patch} not be indented and leave that to the template This removes some unwanted indentation from the tests. In the first case, it's because indent() doesn't indent a blank line. In the second case, it's because we used templating with {patch} and had not requested indentation (but we still got it before this patch). Note that tests will only pass with a very recent Mercurial (one with https://phab.mercurial-scm.org/D7432 applied).

obslog: make {succnodes} be full hex nodes It should be up to the user to shorten the nodeid as much or as little as they like.

obslog: remove now-unused code for plain styling We now always use a non-plain formatter for the non-local-filtering code paths, so we can remove the code for plain styling. I couldn't figure out how to replace the fm.formatlist() by something less about formatting, so I've only removed the irrelevant arguments from those calls.

obslog: redefine default output as a template, unless -f was given This was easier than I expected to do without affecting any test output at all. `hg obslog -f` is pretty broken with templating. For example, it inserts a single "date" field, but it provides two values for it if the dates are different. That results in a traceback when running e.g. `hg obslog -f -Tfoo` with non-local obsmarkers with different dates. We need to figure out what we want to put in the template for the filtered case. I've just left it out for now.

obslog: add newline after all markers in non-graphlog to match graphlog I'd also be fine with doing the reverse if that's preferred, but I really want them to be the same so they can use the same template.

obslog: make reason for unavailable patch part of template We need the reason to be in the template in order to be able to templatize the whole output.

obslog: make content and description patches available to templater The code was repeatedly calling fm.write() with the same field ("patch" and "descdiff"). I think that led to the value constantly getting replaced, so when it was used in a template (as {patch} or {descdiff}), it would only get the last value, which was always an empty string. This patch fixes it by writing the full patch to a temporary buffer and then assigning the whole patch to the formatter field.

obslog: rename {desc-diff} to {descdiff} since the former is invalid

tests: demonstrate broken {patch} and {desc-diff} template keywords

topic: drop compat.successorssets(), it's not used The only place in topics that uses successorssets function is in evolvebits.py, and it's using that function from obsutil directly.