Okay-so the option IS --disable-Werror, but you can't invoke it via dh_auto_configure.
dh_autoreconf is not responsible for this as the file is in ./configure. dh_auto_configure automatically adds flags that I copied over using verbose and then added -disable-Werror flag in. This is what the new debian/rules override_dh_auto_configure looks like: override_dh_auto_configure: ./configure --build=x86_64-linux-gnu \ --prefix=/usr \ --includedir=\${prefix}/include \ --mandir=\${prefix}/share/man \ --infodir=\${prefix}/share/info \ --sysconfdir=/etc --localstatedir=/var \ --disable-silent-rules \ --libdir=\${prefix}/lib/x86_64-linux-gnu \ --libexecdir=\${prefix}/lib/x86_64-linux-gnu \ --runstatedir=/run \ --disable-maintainer-mode \ --disable-dependency-tracking \ --disable-Werror The diff will add that and update dependencies.