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

[Richard W.M. Jones]

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.