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/tree_builder.py

@@ -12,10 +12,10 @@ class TreeBuilder:
         ret = []
         prev = None
         for rev in revisions:
-            print(rev, rev.files_hash(self.db))
+            print(rev, rev.files_hash)
             if rev.broken:
                 continue
-            if prev and prev.files_hash(self.db) == rev.files_hash(self.db):
+            if prev and prev.files_hash == rev.files_hash:
                 continue
             ret.append(rev)
             prev = rev
@@ -25,7 +25,7 @@ class TreeBuilder:
         factory_revisions = self.filtered_revisions("openSUSE:Factory", package)
         source_revisions = dict()
         for rev in factory_revisions:
-            print(rev, rev.files_hash(self.db))
+            print(rev, rev.files_hash)
             if rev.request_id:
                 req = Request.find(self.db, rev.request_id)
                 print("  ", req)
@@ -35,5 +35,5 @@ class TreeBuilder:
                         req.source_project, req.source_package
                     )
                 for rev2 in source_revisions.get(key):
-                    if rev2.files_hash(self.db) == rev.files_hash(self.db):
+                    if rev2.files_hash == rev.files_hash:
                         print("    ", rev2)