No need to do anything in TrackMergeTargetBaseVersionStrategy if TrackMergeTarget is disabled or

the currentBranchName is null or empty

Author: EbenZhang

src/GitVersionCore/VersionCalculation/BaseVersionCalculators/TaggedCommitVersionStrategy.cs

@@ -8,13 +8,6 @@ public class TaggedCommitVersionStrategy : BaseVersionStrategy
     {
         public override IEnumerable<BaseVersion> GetVersions(GitVersionContext context)
         {
-            string currentBranchName = null;
-            var head = context.Repository.Head;
-            if (head != null)
-            {
-                currentBranchName = head.CanonicalName;
-            }
-
             var olderThan = context.CurrentCommit.When();
             var allTags = context.Repository.Tags
                 .Where(tag => ((Commit)tag.PeeledTarget()).When() <= olderThan)
@@ -23,7 +16,7 @@ public override IEnumerable<BaseVersion> GetVersions(GitVersionContext context)
                 .Commits
                 .SelectMany(commit =>
                 {
-                    return allTags.Where(t => IsValidTag(context, currentBranchName, t, commit));
+                    return allTags.Where(t => IsValidTag(t, commit));
                 })
                 .Select(t =>
                 {
@@ -66,7 +59,7 @@ protected virtual string FormatSource(VersionTaggedCommit version)
             return string.Format("Git tag '{0}'", version.Tag);
         }
 
-        protected virtual bool IsValidTag(GitVersionContext context, string branchName, Tag tag, Commit commit)
+        protected virtual bool IsValidTag(Tag tag, Commit commit)
         {
             return tag.PeeledTarget() == commit;
         }

src/GitVersionCore/VersionCalculation/BaseVersionCalculators/TrackMergeTargetBaseVersionStrategy.cs

@@ -1,22 +1,40 @@
 namespace GitVersion.VersionCalculation.BaseVersionCalculators
 {
     using System;
+    using System.Collections.Generic;
     using System.Linq;
     using LibGit2Sharp;
 
     public class TrackMergeTargetBaseVersionStrategy : TaggedCommitVersionStrategy
     {
-        protected override bool IsValidTag(GitVersionContext context, string branchName, Tag tag, Commit commit)
+        public override IEnumerable<BaseVersion> GetVersions(GitVersionContext context)
         {
-            if (!string.IsNullOrWhiteSpace(branchName))
+            if(!context.Configuration.TrackMergeTarget)
             {
-                if (context.Configuration.TrackMergeTarget)
-                {
-                    return IsDirectMergeFromCommit(tag, commit);
-                }
+                yield break;
             }
 
-            return false;
+            string currentBranchName = null;
+            var head = context.Repository.Head;
+            if (head != null)
+            {
+                currentBranchName = head.CanonicalName;
+            }
+
+            if (string.IsNullOrWhiteSpace(currentBranchName))
+            {
+                yield break;
+            }
+
+            foreach (var version in base.GetVersions(context))
+            {
+                yield return version;
+            }
+        }
+
+        protected override bool IsValidTag(Tag tag, Commit commit)
+        {
+            return IsDirectMergeFromCommit(tag, commit);
         }
 
         protected override string FormatSource(VersionTaggedCommit version)