tests: try to import modules with Python 3 All of mercurial.* is now using absolute_import. Most of mercurial.* is able to ast parse with Python 3. The next big hurdle is being able to import modules using Python 3. This patch adds testing of hgext.* and mercurial.* module imports in Python 3. As the new test output shows, most modules can't import under Python 3. However, many of the failures are due to a common problem in a highly imported module (e.g. the bytes vs str issue in node.py).

tests: perform an ast parse with Python 3 Previously, test-check-py3-compat.t parsed Python files with Python 2 and looked for known patterns that are incompatible with Python 3. Now that we have a mechanism for invoking Python 3 interpreters from tests, we can expand check-py3-compat.py and its corresponding .t test to perform an additional AST parse using Python 3. As the test output shows, we identify a number of new parse failures on Python 3. There are some redundant warnings for missing parentheses for the print function. Given the recent influx of patches around fixing these, the redundancy shouldn't last for too long.

run-tests: add --with-python3 to define a Python 3 interpreter Currently, very few parts of Mercurial run under Python 3, notably the test harness. We want to write tests that run Python 3. For example, we want to extend test-check-py3-compat.t to parse and load Python files. However, we have a problem: finding appropriate files requires running `hg files` and this requires Python 2 until `hg` works with Python 3. As a temporary workaround, we add --with-python3 to the test harness to allow us to define the path to a Python 3 interpreter. This interpreter is made available to the test environment via $PYTHON3 so tests can run things with Python 3 while the test harness and `hg` invocations continue to run from Python 2. To round out the feature, a "py3exe" hghave check has been added.

crecord: add docblock to handlekeypressed This information is pretty useful when reading the code.