My guess as to why this stopped working is that the API key you use to link github and copr is only good for 180 days and then must be regenerated.

In T896#14685, @nrwahl2 wrote:

XSL has some mechanism for this, and we already have an appropriate logger in C.

Logging a warning via XSL (using xsl:message) looks straightforward. I presume libxslt will send it to stderr... It's not obvious how we'd tell the C caller to log a message, or what it should log. Maybe we could do some before-and-after checking of the CIB XML, but that doesn't seem worth the computational cost or added code complexity.