test: fix self._testdir to use the right mercurial library during testing Currently if you run tests from some other directory other than the `../tests/`, you will get a warning stating ``` warning: Testing with unexpected mercurial lib: mercurial (expected /tmp/hgtests.xxxxxx/install/lib/python/mercurial) ``` This is because the current directory being added to the 'PATH', if the `self._testdir != runtestdir`, owing to this line ``` if self._testdir != runtestdir: path = [self._testdir] + path ``` Also say you ran the tests from the hg base directory, because directory is being added in the PATH (see the above snippet, at that stage the `self._testdir` has the value as `cwd`, owing to a faulty initialization). And since the current directory already has the 'hg', that is used in place of the hg that is installed for the testing purposes in `/tmp/hgtests.xxxxxx/...`. Differential Revision: https://phab.mercurial-scm.org/D5199

tests: conditonalize a difference in test-merge-tools.t on Windows

statprof: clean up unicode/bytes a little I'm not really sure how this worked before, but something perturbed it and what I've got in this change I believe is a little tidier. This fixes test-profile.t on Python 3. Differential Revision: https://phab.mercurial-scm.org/D5210

statprof: add a couple of asserts to avoid storing unicodes I don't feel strongly about this change, so it'd be fine to drop it during review, but it was _extremely_ helpful in drafting the next change. Differential Revision: https://phab.mercurial-scm.org/D5209

tests: add some helpful `|| cat` bits to test-profile.t This way if the hg invocation crashes, you get to see a stacktrace without having to edit the test. Differential Revision: https://phab.mercurial-scm.org/D5208

tests: skip wireproto clientreactor tests on Python 3.6.0-3.6.3 inclusive See comment next to the if statement for sad details. Differential Revision: https://phab.mercurial-scm.org/D5207

contrib: tweak import-checker to always use bytes for module names We could go the other route and make embedded() return this as a bytes, but then it would be harder to portably doctest, so I prefer this option. Differential Revision: https://phab.mercurial-scm.org/D5206

contrib: fix import-checker to not b'' module names on Python 3 Caught by the doctests. Differential Revision: https://phab.mercurial-scm.org/D5205

tests: add a critical flush() to run-tests.py to make output stable on py3 Differential Revision: https://phab.mercurial-scm.org/D5204

merge-tools: when calling external merge tool, describe the resolve inputs It is a common complaint that a user will be running some operation (histedit, rebase, evolve, etc.), get into a merge-conflict situation, and not understand what they are seeing - it is possible that the merge tool is configured to display the hash, but it's difficult for most merge tools to display a good snippet of the description. In the worst case, configuring this template will lead to output that is immediately covered by a terminal application, maybe the user can hit ctrl-z to see it. In the common case, the output will be in a terminal window and a GUI program will start, and it should be possible to view both the terminal and the GUI program at the same time. Differential Revision: https://phab.mercurial-scm.org/D5094

templatekw: deprecate p1rev/p2rev/p1node/p2node in favor of p1/p2

templatekw: add p1/p2 keywords which switches the current ctx This is just an example of mappingdict. I have no idea what should be displayed as {p1|json}. Currently it is an empty dict since {'ctx'} isn't displayable, which is clearly useless and should be changed later.

templater: add wrapper for a single template mapping This can be used to nest template mappings without inserting a sequence-like layer. See the next patch for example.

templatekw: extract internal "{rev}:{node|formatnode}" template to constant This will be used later.

test: remove changes preparing the drop of `HGMERGE` These changes are no longer necessary so we better drop them.

run-tests: define the default merge tool through configuration Using the `HGMERGE` environment variable generates confusion as it overrides any value set through configuration. By setting the default value through the default HGRC, the usual overriding rules apply and it should reduce confusion.