"Unpeel" annotated tags to get correct changeset

If we just parse the object id of the reference for annotated tags, we
get the annotated tag object and not the reference the tag refers to.

scm-plugins/scm-git-plugin/src/main/java/sonia/scm/repository/spi/GitTagsCommand.java

@@ -127,7 +127,7 @@ public class GitTagsCommand extends AbstractGitCommand implements TagsCommand {
       Tag tag = null;
 
       try {
-        RevObject revObject = revWalk.parseAny(ref.getObjectId());
+        RevObject revObject = GitUtil.getCommit(repository, revWalk, ref);
 
         if (revObject != null) {
           String name = GitUtil.getTagName(ref);