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.

topic: drop compat.getmarkers() and use obsutil.getmarkers() directly The function in question was moved from obsolete to obsutil in a14e2e7f7d1f (hg 4.3). See also 6aff4bb3970d for hgext3rd/evolve.