enhanced branches config

Author: Yannis Guedel

GitVersionCore.Tests/ConfigProviderTests.cs

@@ -64,6 +64,7 @@ public void CanInheritVersioningMode()
         var config = ConfigurationProvider.Provide(gitDirectory, fileSystem);
         config.Branches["develop"].VersioningMode.ShouldBe(VersioningMode.ContinuousDeployment);
         config.Release.VersioningMode.ShouldBe(VersioningMode.ContinuousDelivery);
+        config.Develop.Tag.ShouldBe("unstable");
     }
 
     [Test]

GitVersionCore/Configuration/Config.cs

@@ -76,10 +76,21 @@ public Dictionary<string, BranchConfig> Branches
             }
             set
             {
-                value.ToList().ForEach(_ => branches[_.Key] = _.Value);
+                value.ToList().ForEach(_ => branches[_.Key] = MergeObjects(branches[_.Key],  _.Value));
             }
         }
 
+        private T MergeObjects<T>(T target, T source)
+        {
+            typeof(T).GetProperties()
+                .Where(prop => prop.CanRead && prop.CanWrite)
+                .Select(_ => new {prop = _, value =_.GetValue(source, null) } )
+                .Where(_ => _.value != null)
+                .ToList()
+                .ForEach(_ => _.prop.SetValue(target, _.value, null));
+            return target;
+        }
+
         [YamlAlias("tag-prefix")]
         public string TagPrefix { get; set; }