[dak/master] update-suite: Handle case of not installing new packages.

[Ansgar Burchardt <ansgar@debian.org>]

---
 dak/update_suite.py |    4 ++++
 1 file changed, 4 insertions(+)

diff --git a/dak/update_suite.py b/dak/update_suite.py
index 0d2de5c..6043dd2 100644
--- a/dak/update_suite.py
+++ b/dak/update_suite.py
@@ -187,6 +187,8 @@ class SuiteUpdater(object):
                       .filter(ArchiveFile.archive_id == suite.archive_id)
 
     def install_binaries(self, binaries, suite):
+        if len(binaries) == 0:
+            return
         # If origin and target suites are in the same archive, we can skip the
         # overhead from ArchiveTransaction.copy_binary()
         if self.origin.archive_id == suite.archive_id:
@@ -207,6 +209,8 @@ class SuiteUpdater(object):
                       .filter(ArchiveFile.archive_id == suite.archive_id)
 
     def install_sources(self, sources, suite):
+        if len(sources) == 0:
+            return
         # If origin and target suites are in the same archive, we can skip the
         # overhead from ArchiveTransaction.copy_source()
         if self.origin.archive_id == suite.archive_id:
-- 
1.7.10.4