wireproto: expose the list of getbundle arguments to extensions For now, getbundle accepts a fixed number of arguments: ``heads``, ``common`` and ``bundlecaps``. We make this list exposed at the module level to let extensions add content there. This is important for extensions that wish to use bundle2 for other contents than changegroup.

run-tests: write .err files earlier Earlier refactoring of run-tests.py accidentally broke --interactive and external diff generation by not having .err files written before they are consulted. This patch fixes that.

run-tests: exit with non-0 exit code when tests fail or warn As part of the run-tests.py refactor, run-tests.py accidentally started exiting with 0 for most test runs. This patch restores the expected behavior.