metalk8s_sysctl.has_precedence incorrectly attempts to interpolate %-prefixed sequences

[gdemonet]

Component: salt

What happened:

Some config file in /etc/sysctl.d containing:

kernel.core_pattern=/var/tmp/core-%e-%p-%t

Running bootstrap.sh ends up failing with:

----------
          ID: Set sysctl net.bridge.bridge-nf-call-ip6tables value to 1
    Function: metalk8s_sysctl.present
        Name: net.bridge.bridge-nf-call-ip6tables
      Result: False
     Comment: An exception occurred in this state: Traceback (most recent call last):
                File "/usr/lib/python3.6/site-packages/salt/state.py", line 2154, in call
                  *cdata["args"], **cdata["kwargs"]
                File "/usr/lib/python3.6/site-packages/salt/loader.py", line 2106, in wrapper
                  return f(*args, **kwargs)
                File "/var/cache/salt/minion/extmods/states/metalk8s_sysctl.py", line 29, in present
                  __salt__["metalk8s_sysctl.has_precedence"](name, value, config, strict)
                File "/var/cache/salt/minion/extmods/modules/metalk8s_sysctl.py", line 99, in has_precedence
                  sysctl = dict(parser.items("global"))
                File "/usr/lib64/python3.6/configparser.py", line 858, in items
                  return [(option, value_getter(option)) for option in d.keys()]
                File "/usr/lib64/python3.6/configparser.py", line 858, in <listcomp>
                  return [(option, value_getter(option)) for option in d.keys()]
                File "/usr/lib64/python3.6/configparser.py", line 855, in <lambda>
                  section, option, d[option], d)
                File "/usr/lib64/python3.6/configparser.py", line 394, in before_get
                  self._interpolate_some(parser, option, L, value, section, defaults, 1)
                File "/usr/lib64/python3.6/configparser.py", line 444, in _interpolate_some
                  "found: %r" % (rest,))
              configparser.InterpolationSyntaxError: '%' must be followed by '%' or '(', found: '%e-%p-%t'
     Started: 17:47:25.657044
    Duration: 7.262 ms
     Changes:

What was expected: Such config file is accepted by sysctl, we should not fail. Also, if we do, we should wrap the error in a CommandExecutionError.

Resolution proposal (optional): Disable interpolation with ConfigParser(interpolation=None).