Some buckets fail to download after some time

[Arturo Filastò]

It's not fully reproducible, but I was able to reproduce it after running the pip version of oonidata, like so:

% oonidata sync --probe-cc RU --start-day 2023-10-01 --end-day 2023-10-31 --test-name web_connectivity --output-dir Russia/2023/

Downloading measurements for 2023-10-01 - 2023-10-31 into Russia/2023
probe_cc: RU
test_name: web_connectivity
downloaded 20/720:   3%|█▌                                                          | 1.35G/51.9G [01:26<53:54, 15.6MB/s]
multiprocessing.pool.RemoteTraceback:
"""
Traceback (most recent call last):
  File "/Users/art/.pyenv/versions/3.11.7/lib/python3.11/multiprocessing/pool.py", line 125, in worker
    result = (True, func(*args, **kwds))
                    ^^^^^^^^^^^^^^^^^^^
  File "/Users/art/.pyenv/versions/3.11.7/envs/oonidata/lib/python3.11/site-packages/oonidata/dataclient.py", line 651, in download_file_entry_list
    for msmt_dict in iter_measurements(
  File "/Users/art/.pyenv/versions/3.11.7/envs/oonidata/lib/python3.11/site-packages/oonidata/dataclient.py", line 594, in iter_measurements
    for msmt in fe.stream_measurements():
  File "/Users/art/.pyenv/versions/3.11.7/envs/oonidata/lib/python3.11/site-packages/oonidata/dataclient.py", line 278, in stream_measurements
    yield from stream_postcan(body)
  File "/Users/art/.pyenv/versions/3.11.7/envs/oonidata/lib/python3.11/site-packages/oonidata/dataclient.py", line 162, in stream_postcan
    post = orjson.loads(in_file.read())
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
orjson.JSONDecodeError: unexpected character: line 1 column 17 (char 16)
"""

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/Users/art/.pyenv/versions/oonidata/bin/oonidata", line 8, in <module>
    sys.exit(cli())
             ^^^^^
  File "/Users/art/.pyenv/versions/3.11.7/envs/oonidata/lib/python3.11/site-packages/click/core.py", line 1157, in __call__
    return self.main(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/art/.pyenv/versions/3.11.7/envs/oonidata/lib/python3.11/site-packages/click/core.py", line 1078, in main
    rv = self.invoke(ctx)
         ^^^^^^^^^^^^^^^^
  File "/Users/art/.pyenv/versions/3.11.7/envs/oonidata/lib/python3.11/site-packages/click/core.py", line 1688, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/art/.pyenv/versions/3.11.7/envs/oonidata/lib/python3.11/site-packages/click/core.py", line 1434, in invoke
    return ctx.invoke(self.callback, **ctx.params)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/art/.pyenv/versions/3.11.7/envs/oonidata/lib/python3.11/site-packages/click/core.py", line 783, in invoke
    return __callback(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/art/.pyenv/versions/3.11.7/envs/oonidata/lib/python3.11/site-packages/oonidata/cli/command.py", line 102, in sync
    sync_measurements(
  File "/Users/art/.pyenv/versions/3.11.7/envs/oonidata/lib/python3.11/site-packages/oonidata/dataclient.py", line 721, in sync_measurements
    for fe_size in pool.imap_unordered(
  File "/Users/art/.pyenv/versions/3.11.7/lib/python3.11/multiprocessing/pool.py", line 873, in next
    raise value
orjson.JSONDecodeError: unexpected character: line 1 column 17 (char 16)