Fix Git reset for Maven upgrade command.

src/main/java/org/springframework/data/release/infra/InfrastructureCommands.java

@@ -93,6 +93,8 @@ public class InfrastructureCommands extends TimedCommand {
 
 		logger.log(iteration, "Applying Maven wrapper upgrades to Spring Data…");
 
+		git.prepare(iteration);
+
 		infra.upgradeMavenVersion(iteration);
 	}
 

src/main/java/org/springframework/data/release/infra/InfrastructureOperations.java

@@ -135,8 +135,6 @@ public class InfrastructureOperations extends TimedCommand {
 			throw new IllegalStateException("No version to upgrade found!");
 		}
 
-		git.checkout(iteration.getTrain(), false);
-
 		List<Project> projectsToUpgrade = dependencies
 				.getProjectsToUpgradeMavenWrapper(dependencyVersions.get(Dependencies.MAVEN), iteration);