[Libguestfs] [PATCH nbdkit v3 0/7] Implement nbdkit API v2 for Python plugins.

v2 was here: https://www.redhat.com/archives/libguestfs/2019-November/msg00163.html I pushed patch 1 (with spelling fix), patch 4 and patch 5 since those were previously ACKed on the list. Differences in v3: - Add error checking to PyModule_AddIntConstant. - Use API_VERSION constant instead of function. - Add max API version supported to --dump-plugin output. - Print API_VERSION selected by the module in debug output. - Allow .cache to be used from v1 API. Since it's a newly added function we just use the same API as v2. Differences in tests patch: - converted the test suite to use unittest - use base64 instead of codecs module (also this means we strip whitespace around pickled+base64 string) - formatting to avoid long lines - whitespace consistency - remove "python" mention in test-lang-plugins.c since it's no longer used - remove #! from test-python-plugin.py as it is not needed - add tests of pread + various buffer types Rich.