Attempt to fix issue where commit message is counted twice.

When multiple base versions will result in the same semantic version, the oldest is selected for commit counting. The same base version commit is used to find intermediate commits for commit mesage increments. The attempt here is to use the oldest base version also for the semantic version such that the commit message increments are not done on a semver from another base version.

Author: LarsAndreasEk

src/GitVersionCore.Tests/IntegrationTests/ReleaseBranchScenarios.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Generic;
 using System.Diagnostics;
 using GitTools;
 using GitTools.Testing;
@@ -375,7 +376,7 @@ public void ReleaseBranchShouldUseBranchNameVersionDespiteBumpInPreviousCommit()
 
             Commands.Checkout(fixture.Repository, fixture.Repository.CreateBranch("release/2.0"));
 
-            fixture.AssertFullSemver("2.0.0-beta.1+0");
+            fixture.AssertFullSemver("2.0.0-beta.1+2");
         }
     }
 }

src/GitVersionCore/VersionCalculation/BaseVersionCalculator.cs

@@ -51,7 +51,9 @@ public BaseVersion GetBaseVersion(GitVersionContext context)
                 BaseVersion baseVersionWithOldestSource;
                 if (matchingVersionsOnceIncremented.Any())
                 {
-                    baseVersionWithOldestSource = matchingVersionsOnceIncremented.Aggregate((v1, v2) => v1.Version.BaseVersionSource.Committer.When < v2.Version.BaseVersionSource.Committer.When ? v1 : v2).Version;
+                    var oldest = matchingVersionsOnceIncremented.Aggregate((v1, v2) => v1.Version.BaseVersionSource.Committer.When < v2.Version.BaseVersionSource.Committer.When ? v1 : v2);
+                    baseVersionWithOldestSource = oldest.Version;
+                    maxVersion = oldest;
                     Logger.WriteInfo(string.Format(
                         "Found multiple base versions which will produce the same SemVer ({0}), taking oldest source for commit counting ({1})",
                         maxVersion.IncrementedVersion,