gistfile1.txt

diff --git a/DistUpgrade/DistUpgradeCache.py b/DistUpgrade/DistUpgradeCache.py
index 0692ef90c..27a45d796 100644
--- a/DistUpgrade/DistUpgradeCache.py
+++ b/DistUpgrade/DistUpgradeCache.py
@@ -449,6 +449,23 @@ class MyCache(apt.Cache):
         if pkg in self:
             self._depcache.mark_delete(self[pkg]._pkg, True)
 
+    def _do_not_install(self, pkgname, reason):
+        if (pkgname in self
+            and not self[pkgname].is_installed
+            and self[pkgname].marked_install):
+            self.mark_remove(pkgname, reason)
+
+    def do_not_install_rule(self):
+        """ run after the dist-upgrade to ensure that certain
+            packages are not newly installed """
+        # We handle provides here, so we can mark e.g. mail-transport-agent as something we do not
+        # want a release upgrade to pull in by depends.
+        for pkgname in self.config.getlist("Distro", "DoNotInstallPkgs"):
+            if pkgname in self:
+                self._do_not_install(pkgname, "Distro KeepInstalledPkgs rule")
+                for _, _, provver in in self[pkgname].provides_list:
+                    self._do_not_install(provver.parent_pkg.name, "Distro KeepInstalledPkgs rule")
+
     def _keep_installed(self, pkgname, reason):
         if (pkgname in self
             and self[pkgname].is_installed
@@ -631,6 +648,9 @@ class MyCache(apt.Cache):
             # check that everything in priority required is installed
             self.checkPriority()
 
+            # see if our KeepInstalled rules are honored
+            self.do_not_install_rule()
+
             # see if our KeepInstalled rules are honored
             self.keep_installed_rule()