Trying to work around issues with checking out tags

Author: marcingrzejszczak

src/main/java/io/micrometer/release/train/Git.java

@@ -30,7 +30,7 @@ class Git {
     void changeTag(String tag) {
         log.info("Changing git head to tag [{}]", tag);
         processRunner.run("git", "fetch", "origin", "refs/tags/" + tag);
-        processRunner.run("git", "checkout", tag);
+        processRunner.run("git", "checkout", "FETCH_HEAD");
     }
 
 }

src/test/java/io/micrometer/release/train/GitTests.java

@@ -30,7 +30,7 @@ void should_checkout_tag() {
         git.changeTag("v1.2.3");
 
         then(processRunner).should().run("git", "fetch", "origin", "refs/tags/v1.2.3");
-        then(processRunner).should().run("git", "checkout", "v1.2.3");
+        then(processRunner).should().run("git", "checkout", "FETCH_HEAD");
     }
 
 }