IndexDiff: Remove unnecessary changesExist flag

Instead of setting a boolean when a difference record is found, return
false from diff() only if all of the collections are empty.  When all
of them are empty, no difference was found.

Change-Id: I555fef37adb764ce253481751071c53ad12cf416
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

org.eclipse.jgit/src/org/eclipse/jgit/lib/IndexDiff.java

@@ -168,7 +168,6 @@ public class IndexDiff {
 	 * @throws IOException
 	 */
 	public boolean diff() throws IOException {
-		boolean changesExist = false;
 		dirCache = repository.readDirCache();
 
 		TreeWalk treeWalk = new TreeWalk(repository);
@@ -202,12 +201,10 @@ public class IndexDiff {
 							!= dirCacheIterator.getEntryRawMode()) {
 						// in repo, in index, content diff => changed
 						changed.add(treeWalk.getPathString());
-						changesExist = true;
 					}
 				} else {
 					// in repo, not in index => removed
 					removed.add(treeWalk.getPathString());
-					changesExist = true;
 					if (workingTreeIterator != null)
 						untracked.add(treeWalk.getPathString());
 				}
@@ -215,13 +212,11 @@ public class IndexDiff {
 				if (dirCacheIterator != null) {
 					// not in repo, in index => added
 					added.add(treeWalk.getPathString());
-					changesExist = true;
 				} else {
 					// not in repo, not in index => untracked
 					if (workingTreeIterator != null
 							&& !workingTreeIterator.isEntryIgnored()) {
 						untracked.add(treeWalk.getPathString());
-						changesExist = true;
 					}
 				}
 			}
@@ -230,18 +225,22 @@ public class IndexDiff {
 				if (workingTreeIterator == null) {
 					// in index, not in workdir => missing
 					missing.add(treeWalk.getPathString());
-					changesExist = true;
 				} else {
 					if (workingTreeIterator.isModified(
 							dirCacheIterator.getDirCacheEntry(), true)) {
 						// in index, in workdir, content differs => modified
 						modified.add(treeWalk.getPathString());
-						changesExist = true;
 					}
 				}
 			}
 		}
-		return changesExist;
+
+		if (added.isEmpty() && changed.isEmpty() && removed.isEmpty()
+				&& missing.isEmpty() && modified.isEmpty()
+				&& untracked.isEmpty())
+			return false;
+		else
+			return true;
 	}
 
 	/**