You're right, it's technically more correct to have that lsb-base dependency (with the version), even if in most cases lsb-base is always around. This delta could be forwarded to Debian.
The idea is to keep the Debian diff as small as possible, which will allow simpler merges in the future. So even if in some cases Debian is cosmetically wrong, it makes sense to keep the Debian syntax, which means in your case keeping Debian whitespaces. That's just a personal advice, it doesn't mean that your merge would be wrong if you kept your syntax :)
@Andres:
You're right, it's technically more correct to have that lsb-base dependency (with the version), even if in most cases lsb-base is always around. This delta could be forwarded to Debian.
The idea is to keep the Debian diff as small as possible, which will allow simpler merges in the future. So even if in some cases Debian is cosmetically wrong, it makes sense to keep the Debian syntax, which means in your case keeping Debian whitespaces. That's just a personal advice, it doesn't mean that your merge would be wrong if you kept your syntax :)