puppetlabs-stdlib: file_line match not working in v4.20.0

Basic Info
*Module Version:v4.20.0
*Puppet Version: 4.10.4 (2017_2.2)
*OS Name/Version: Redhat Linux 7.2

Describe your issue in as much detail as possible...
file _line match and replace a string is not working..

if ($::hostname =~ /(wooddesktop)/) {

file_line { 'system.conf':

        ensure => 'present',

        path => "/etc/systemd/system.conf",

        line => 'LogLevel=notice',

        match => '^#LogLevel\$',

        #match => '^#relayhost\ =\ uucphost$',

        append_on_no_match => false,

  }

Desired Behavior:
match string ^#LogLevel, replace with LogLevel=notice

Actual Behavior:
added append_on_no_match => false,
to stop appending the "line: every run. tried undef, had not effect

Please take a moment and attach any relevant log output and/or manifests. This will help us immensely when troubleshooting the issue.