file {} fails to verify certificate when downloading via https

Puppet Version: See above
Puppet Server Version: 6.9.0
OS Name/Version: Ubuntu 18.04 LTS (not listed in drop down above, neither for agent, nor for master)

After updating Puppet agent to 6.14.0 we see a failure in certificate validation when using a file resource with a https:// URL, which didn't happen before. The resource in question looks like this (simplyfied):

file { 'cache_node_jar':

  path    => "/tmp/build-cache-node-8.1.jar",

  source  => "https://docs.gradle.com/build-cache-node/jar/build-cache-node-8.1.jar",

  ensure  => present,

}

which produced the following error:

certificate verify failed [unable to get local issuer certificate for CN=CloudFlare Inc ECC CA-2,O=CloudFlare\, Inc.,L=San Francisco,ST=CA,C=US]

Since we have a Nexus server running in our environment (which also has a valid certificate, issued by Comodo), I set up a cache repository there and changed the URL, so that the resource now looks like this: 

file { 'cache_node_jar':

  path    => "/tmp/build-cache-node-8.1.jar",

  source  => "https://nexus.ourdomain.com/repository/gradle-cache/build-cache-node-8.1.jar",

  ensure  => present,

}

but this only led to a small change in the error message:

certificate verify failed [self signed certificate in certificate chain for CN=AddTrust External CA Root,OU=AddTrust External TTP Network,O=AddTrust AB,C=SE]

but, as mentioned, the certificate is not self-signed. Downgrading the agent back to 6.13.0 resolved the problem.

Desired Behavior:

Certificate should be correclty validated as in 6.13.0.

Actual Behavior:

See above.

Please also consider this a feature request to add an option to file resources to skip certificate validation. Most other tools I know have such an option.