Fix rsync publishing units it shouldn't

Fixes an issue with rsync logic where some units which have
not yet been published by the predistributor are included
with rsync publishes.

closes pulp#2791
https://pulp.plan.io/issues/2791

(cherry picked from commit 82651e0)

server/pulp/plugins/rsync/publish.py

@@ -348,6 +348,10 @@ def __init__(self, repo, publish_conduit, config, distributor_type):
         else:
             date_filter = None
 
+            if self.predistributor:
+                end_date = self.predistributor["last_publish"]
+                date_filter = self.create_date_range_filter(None, end_date=end_date)
+
         self.symlink_list = []
         self.content_unit_file_list = []
         self.symlink_src = os.path.join(self.get_working_dir(), '.relative/')
@@ -368,10 +372,12 @@ def is_fastforward(self):
             force_full |= predistributor_force_full
             if entry.get("result", "error") == "error":
                 force_full = True
+
         if self.last_published:
             last_published = self.last_published.replace(tzinfo=None)
         else:
             last_published = None
+
         if self.last_deleted:
             last_deleted = self.last_deleted.replace(tzinfo=None)
         else: