run-tests: test result shows when a failed test could not start a server Failing to start a server happens regularly, at least on windows buildbot. Such a failure often has nothing to do with the test, but with the environment. But half the test output can change because some data is missing. Therefore this is worth an extended error message. Detect the server failure in the diff output because it is most reliable there. Checking the output only does not show if the server failure was expected. Old failure message when server start failed: Failed test-serve.t: output changed New message: Failed test-serve.t: serve failed and output changed

commit: --edit/-e to force edit of otherwise-supplied commit message The --edit/-e option for the 'commit' command forces editor, even when a commit message has been provided already by other means, such as by the -m or -l options.

bundle2: directly feed part to readbundle Now that part payload can be read like a stream, we can directly use it to feed the unbundle10 process.

bundle2: lazy unbundle of part payload The `unbundle` part gains a `read` method to retrieve payload content. This method behaves as a python file-like read method. The bundle-processing code is updated to make sure a part is fully consumed before another one is extracted. Test output changes because the debug output is even more interleaved now.

util: support None size in chunkbuffer.read() When no size is provided, read the whole buffer. This aligns with the usual behavior of `read()` in python.

bundle2: lazily iterate over bundle parts in the test We used to create a list to know the number of parts in the bundle. This prevents any lazy reading as planned for real usage. The list creation is dropped. Some test output changed as debug output is now interleaved with command output.