commit 8ae3ad9a8bb297c39bc287802b3220e497dfbbcc
Author: Michal Domonkos <mdomonko@redhat.com>
Date:   Thu Apr 14 13:36:02 2016 +0200

    Make YumHistoryRpmdbProblem objects hashable. BZ 1292087
    
    Let's use rpid for that to ensure we get the same hash value for objects
    that compare equal (which is iff their rpid's match, see __cmp__).

diff --git a/yum/history.py b/yum/history.py
index d08837c..f1295de 100644
--- a/yum/history.py
+++ b/yum/history.py
@@ -244,6 +244,9 @@ class YumHistoryRpmdbProblem:
         ret = cmp(self.rpid, other.rpid)
         return ret
 
+    def __hash__(self):
+        return hash(self.rpid)
+
     def _getProbPkgs(self):
         if self._loaded_P is None:
             self._loaded_P = sorted(self._history._old_prob_pkgs(self.rpid))