Polish "Use git.commit.id.abbrev if present" contribution

Closes gh-8781

spring-boot/src/main/java/org/springframework/boot/info/GitProperties.java

 /*
- * Copyright 2012-2016 the original author or authors.
+ * Copyright 2012-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -54,11 +54,10 @@ public class GitProperties extends InfoProperties {
 	 * @return the short commit id
 	 */
 	public String getShortCommitId() {
-		String idAbbrev = get("commit.id.abbrev");
-		if (idAbbrev != null) {
-			return idAbbrev;
+		String shortId = get("commit.id.abbrev");
+		if (shortId != null) {
+			return shortId;
 		}
-
 		String id = getCommitId();
 		if (id == null) {
 			return null;

spring-boot/src/test/java/org/springframework/boot/info/GitPropertiesTests.java

 /*
- * Copyright 2012-2016 the original author or authors.
+ * Copyright 2012-2017 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -73,6 +73,14 @@ public class GitPropertiesTests {
 		assertThat(properties.get("commit.time")).isEqualTo("2016-03-04 15:22:24");
 	}
 
+	@Test
+	public void shortCommitUsedIfPresent() {
+		GitProperties properties = new GitProperties(
+				createProperties("master", "abcdefghijklmno", "abcdefgh", "1457527123"));
+		assertThat(properties.getCommitId()).isEqualTo("abcdefghijklmno");
+		assertThat(properties.getShortCommitId()).isEqualTo("abcdefgh");
+	}
+
 	@Test
 	public void shortenCommitIdShorterThan7() {
 		GitProperties properties = new GitProperties(
@@ -89,14 +97,6 @@ public class GitPropertiesTests {
 		assertThat(properties.getShortCommitId()).isEqualTo("abcdefg");
 	}
 
-	@Test
-	public void shortCommitIdCustomLength() {
-		GitProperties properties = new GitProperties(
-				createProperties("master", "abcdefghijklmno", "abcdefgh", "1457527123"));
-		assertThat(properties.getCommitId()).isEqualTo("abcdefghijklmno");
-		assertThat(properties.getShortCommitId()).isEqualTo("abcdefgh");
-	}
-
 	private static Properties createProperties(String branch, String commitId,
 			String commitIdAbbrev, String commitTime) {
 		Properties properties = new Properties();