rpmbuild: use values with evaluated macros

See fedora-copr#2848 (comment)

rpmbuild/copr_rpmbuild/helpers.py

@@ -406,7 +406,7 @@ def __init__(self, path):
         self.tags = self.spec.tags(self.spec.parsed_sections.package).content
 
     def __getattr__(self, name):
-        value = getattr(self.spec, name)
+        value = getattr(self.tags, name).value
         if name == "epoch" and value is not None:
             return int(value)
         return value