Comment 1 for bug 1834779

This indicates an error in your input file. I'm guessing the parenthesized number in the Source: field is what causes the parse error, but I'm not in a place where I can check this.

equivs-build uses the data in your input file to populate a number of templates which are required in all Debian packages. Sometimes errors are passed through and cause one of the build toolchain utilities to fail with an error. Perhaps see also upstream bug https://bugs.debian.org/219188