Create fake revisions for every commit in the base of a linked package

This is a rather complex operation, but whenever a package changes in
Factory, the inherited package gets a shadow revision consisting of the
3-way merge. If this happens due to a request being accepted, this is
actually in most cases also commited by 'buildservice-autocommit',
so we're making sure this is always happening (and are actually
duplicating revisions in cases that we filter out later as empty
commits).

To differenciate the fake revisions from the real revisions, I add
a fraction part

lib/obs_revision.py

@@ -56,7 +56,7 @@ class OBSRevision:
         return self
 
     def __str__(self):
-        return f"Rev {self.project}/{self.rev} Md5 {self.srcmd5} {self.time} {self.userid} {self.request_number}"
+        return f"Rev {self.project}/{self.package}/{self.rev}.0 Md5 {self.srcmd5} {self.time} {self.userid} {self.request_number}"
 
     def __repr__(self):
         return f"[{self.__str__()}]"