spec_parser confused by multibuild and ternary operations

[DimStar77]

I was trying to use some modern constructs in a spec file:

%define flavor @BUILD_FLAVOR@%{nil}

Name:           c-ares%["%{flavor}" == "" ? "" : "-%{flavor}"]

For RPM this is all right, but osc service ra source_validator fails with:

Factory/c-ares> osc service ra source_validator
- package has baselibs.conf: (unchanged)
ERROR: c-ares.changes not a subpackage, please remove

Some extra debug added in 45-stale-changes reveals it's expecting these names:
c-ares- c-ares-testsuite (note the trailing - in the first name;i.e it fails to understand that the nil flavor would not have a dash