Як виправити bup make AssertionError: assert not date.startswith(b'$Format')

set -e; bup_ver=$(./bup version); \
echo "s,%BUP_VERSION%,$bup_ver,g" > Documentation/substvars.tmp; \
echo "s,%BUP_DATE%,$bup_ver,g" >> Documentation/substvars.tmp
Traceback (most recent call last):
  File "/usr/lib/python3.10/runpy.py", line 196, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File "/usr/lib/python3.10/runpy.py", line 86, in _run_code
    exec(code, run_globals)
  File "/home/uli/dev/deb-buildscripts/bup/lib/bup/main.py", line 181, in <module>
    cmd_module = import_module('bup.cmd.'
  File "/usr/lib/python3.10/importlib/__init__.py", line 126, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1050, in _gcd_import
  File "<frozen importlib._bootstrap>", line 1027, in _find_and_load
  File "<frozen importlib._bootstrap>", line 1006, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 688, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 883, in exec_module
  File "<frozen importlib._bootstrap>", line 241, in _call_with_frames_removed
  File "/home/uli/dev/deb-buildscripts/bup/lib/bup/cmd/version.py", line 5, in <module>
    from bup import options, version
  File "/home/uli/dev/deb-buildscripts/bup/lib/bup/version.py", line 20, in <module>
    assert not date.startswith(b'$Format')
AssertionError
make: *** [GNUmakefile:252: Documentation/substvars] Fehler 1