Set module_hotfixes on repos created for local builds to allow using modular packages in non-modular repos

This fixes an issue that causes module-build-macros to fail during a local
build when a module buildrequires a non-base module.

module_build_service/builder/MockModuleBuilder.py

@@ -223,6 +223,8 @@ class MockModuleBuilder(GenericBuilder):
         self.yum_conf += "[%s]\n" % name
         self.yum_conf += "name=%s\n" % name
         self.yum_conf += "baseurl=%s\n" % baseurl
+        # See https://dnf.readthedocs.io/en/latest/modularity.html#hotfix-repositories
+        self.yum_conf += "module_hotfixes=true\n"
         self.yum_conf += extra
         self.yum_conf += "enabled=1\n\n"