Pipe Backend doesn't handle ENTs correctly

[dwfreed]

• This is not a support question, I have read about opensource and will send support questions to the IRC channel, GitHub Discussions or the mailing list.
• I have read and understood the 'out in the open' support policy

• Program: Authoritative
• Issue type: Bug report

Short description

Pipe Backend provides no mechanism to correctly return an ENT (empty non-terminal). With nothing for the content field, it errors with "Coprocess returned incomplete or empty line in data section for query" because stringtok swallows trailing delimiters. Returning "" for content, or anything else, causes it to error when parsing with "When parsing ENT trailing data was not parsed"

Other information

To work around this issue, you can instead return a TXT record with "" for content. Another alternative, if feasible, would be to use Remote Backend instead, which does not have this issue.