Merge #19632: test: Catch decimal.InvalidOperation from TestNodeCLI#send_cli

82fc401 test: Catch decimal.InvalidOperation from TestNodeCLI#send_cli (Ben Woosley)

Pull request description:

  `decimal.InvalidOperation` is a special case of a float parsing error, which
  presumably should be handled in the same way as a general parsing error,
  rather than blow up.

  Alternatives include: logging the error, or re-raising with more information.

  Example log output:
  ```
      File "/home/travis/build/bitcoin/bitcoin/ci/scratch/build/bitcoin-i686-pc-linux-gnu/test/functional/test_framework/test_framework.py", line 603, in sync_all
        self.sync_blocks(nodes)
      File "/home/travis/build/bitcoin/bitcoin/ci/scratch/build/bitcoin-i686-pc-linux-gnu/test/functional/test_framework/test_framework.py", line 568, in sync_blocks
        best_hash = [x.getbestblockhash() for x in rpc_connections]
      File "/home/travis/build/bitcoin/bitcoin/ci/scratch/build/bitcoin-i686-pc-linux-gnu/test/functional/test_framework/test_framework.py", line 568, in <listcomp>
        best_hash = [x.getbestblockhash() for x in rpc_connections]
      File "/home/travis/build/bitcoin/bitcoin/ci/scratch/build/bitcoin-i686-pc-linux-gnu/test/functional/test_framework/test_node.py", line 571, in __call__
        return self.cli.send_cli(self.command, *args, **kwargs)
      File "/home/travis/build/bitcoin/bitcoin/ci/scratch/build/bitcoin-i686-pc-linux-gnu/test/functional/test_framework/test_node.py", line 639, in send_cli
        return json.loads(cli_stdout, parse_float=decimal.Decimal)
      File "/usr/lib64/python3.6/json/__init__.py", line 367, in loads
        return cls(**kw).decode(s)
      File "/usr/lib64/python3.6/json/decoder.py", line 339, in decode
        obj, end = self.raw_decode(s, idx=_w(s, 0).end())
      File "/usr/lib64/python3.6/json/decoder.py", line 355, in raw_decode
        obj, end = self.scan_once(s, idx)
    decimal.InvalidOperation: [<class 'decimal.InvalidOperation'>]
  ```
  See: https://travis-ci.org/github/bitcoin/bitcoin/jobs/713502326

ACKs for top commit:
  laanwj:
    ACK 82fc401

Tree-SHA512: 8c102b8bf831b05c5ca4b2e1feb5574dcbaed8cab0b2f22b013c5dfcb81788a38839a163dd1e2c6470ccbe5874214663b84485f45467738fd850ca38d539ae25

Author: laanwj

test/functional/test_framework/test_node.py

@@ -637,7 +637,7 @@ def send_cli(self, command=None, *args, **kwargs):
             raise subprocess.CalledProcessError(returncode, self.binary, output=cli_stderr)
         try:
             return json.loads(cli_stdout, parse_float=decimal.Decimal)
-        except json.JSONDecodeError:
+        except (json.JSONDecodeError, decimal.InvalidOperation):
             return cli_stdout.rstrip("\n")
 
 class RPCOverloadWrapper():