build error, 2

[sdarwin]

Building this PR:

boostorg/json#1109

+ diff-coverage-report/diff-coverage-report.py -D difference -O /jenkins/workspace/json_lcov_PR-1109/diff-report -B /jenkins/workspace/json-target-branch-iteration/coverage_filtered.info -T /jenkins/workspace/json_lcov_PR-1109/coverage_filtered.info -S /jenkins/workspace/json_lcov_PR-1109 -P /jenkins/workspace/json-target-branch-iteration /jenkins/workspace/json_lcov_PR-1109 /jenkins/workspace/boost-root/libs/json /jenkins/workspace/json_lcov_PR-1109 /jenkins/workspace/boost-root/boost /jenkins/workspace/json_lcov_PR-1109/include/boost
Traceback (most recent call last):
  File "/jenkins/workspace/diff-coverage-report/diff-coverage-report.py", line 701, in <module>
    main(sys.argv)
  File "/jenkins/workspace/diff-coverage-report/diff-coverage-report.py", line 33, in main
    files = parse_diff(f, files, source_dir, prefix_map)
            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/jenkins/workspace/diff-coverage-report/diff-coverage-report.py", line 236, in parse_diff
    for l in lines:
  File "<frozen codecs>", line 322, in decode
UnicodeDecodeError: 'utf-8' codec can't decode byte 0xff in position 4061: invalid start byte