CommitCommand: Remove redundant null check

Repository.getWorkTree is annotated as @NonNull, so the check
for it returning null is redundant.

Change-Id: I597b0f774ff857b8900519f14a1a17a904cf7c6f
Signed-off-by: David Pursehouse <david.pursehouse@sonymobile.com>

org.eclipse.jgit/src/org/eclipse/jgit/api/CommitCommand.java

@@ -179,7 +179,7 @@ public class CommitCommand extends GitCommand<RevCommit> {
 
 			processOptions(state, rw);
 
-			if (all && !repo.isBare() && repo.getWorkTree() != null) {
+			if (all && !repo.isBare()) {
 				try (Git git = new Git(repo)) {
 					git.add()
 							.addFilepattern(".") //$NON-NLS-1$