Traceback (most recent call last):
  File "test/lint/lint-include-guards.py", line 88, in <module>
    main()
  File "test/lint/lint-include-guards.py", line 71, in main
    header_file_contents_string = open(header_file, 'r').read()
  File "/usr/lib/python3.6/encodings/ascii.py", line 26, in decode
    return codecs.ascii_decode(input, self.errors)[0]
UnicodeDecodeError: 'ascii' codec can't decode byte 0xce in position 2003: ordinal not in range(128)
^---- failure generated from test/lint/lint-include-guards.py
Python's open(...) seems to be used to open text files without explicitly
specifying encoding="utf8":

test/lint/lint-include-guards.py:        header_file_contents_string = open(header_file, 'r').read()
^---- failure generated from test/lint/lint-python-utf8-encoding.sh
Success: no issues found in 236 source files

src/bench/bench.h seems to be missing the expected include guard:
  #ifndef BITCOIN_BENCH_BENCH_H
  #define BITCOIN_BENCH_BENCH_H
  ...
  #endif // BITCOIN_BENCH_BENCH_H

src/attributes.h seems to be missing the expected include guard:
  #ifndef BITCOIN_ATTRIBUTES_H
  #define BITCOIN_ATTRIBUTES_H
  ...
  #endif // BITCOIN_ATTRIBUTES_H

src/banman.h seems to be missing the expected include guard:
  #ifndef BITCOIN_BANMAN_H
  #define BITCOIN_BANMAN_H
  ...
  #endif // BITCOIN_BANMAN_H

src/bech32.h seems to be missing the expected include guard:
  #ifndef BITCOIN_BECH32_H
  #define BITCOIN_BECH32_H
  ...
  #endif // BITCOIN_BECH32_H