KeyError: 'boto3.assign_funcs' when provisioning with salt

I have provisioning Arvados on a Ubuntu 18.04 VM using the single host salt method. After fixing a bug the provisioning ran successfully but there are errors in the logs of the form:

[DEBUG   ] Could not LazyLoad boto3.assign_funcs: 'boto3.assign_funcs' is not available.
[DEBUG   ] Error loading module.boto3_elasticsearch: __init__ failed
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/salt/", line 1855, in _load_module
  File "/usr/lib/python3/dist-packages/salt/modules/", line 87, in __init__
    __utils__["boto3.assign_funcs"](__name__, "es")
  File "/usr/lib/python3/dist-packages/salt/", line 1354, in __getitem__
    func = super().__getitem__(item)
  File "/usr/lib/python3/dist-packages/salt/utils/", line 108, in __getitem__
    raise KeyError(key)
KeyError: 'boto3.assign_funcs'

The complete provisioning log is here and, as noted, it completes successfully but is there perhaps some step in the (pre) installation that could avoid these messages?