Service "set_version" stopped to work for our project

In the _service file of the project

https://build.opensuse.org/package/show/home:matzfuchs/stromx

I use the tag <service name=“set_version”/> to set the version in the spec-file of a Github-repository to the according git version. The spec-file is here:

https://github.com/uboot/stromx/blob/master/rpm/stromx.spec

The resulting spec-file (with the version set by OBS):

https://build.opensuse.org/package/view_file/home:matzfuchs/stromx/_service:set_version:_service:extract_file:stromx.spec?expand=1

Obviously, this leads to an build error because of the missing version in line 21 (the version is inserted below instead of next to "Version: "). This problem occurred first a couple of months ago, it worked fine before. I would be grateful for any ideas how to resolve this issue.

Alternatively, can anybody point me to a project on OBS which successfully uses <service name=“set_version”/>? Having a look at a working example would definitely help me.