Refactor amazon-s3:// property file loading to support no directory

In the future getDirectory() can return null.  Avoid an NPE here by
refactoring the code to support conditionally skipping a check for
the properties file in the repository directory, falling to only
the user's ~/ file location.

Change-Id: I76f5503d4063fdd9d24b7c1b58e1b09ddf1a5670
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

org.eclipse.jgit/src/org/eclipse/jgit/transport/TransportAmazonS3.java

@@ -126,23 +126,7 @@ public class TransportAmazonS3 extends HttpTransport implements WalkTransport {
 			throws NotSupportedException {
 		super(local, uri);
 
-		Properties props = null;
-		File propsFile = new File(local.getDirectory(), uri.getUser());
-		if (!propsFile.isFile())
-			propsFile = new File(local.getFS().userHome(), uri.getUser());
-		if (propsFile.isFile()) {
-			try {
-				props = AmazonS3.properties(propsFile);
-			} catch (IOException e) {
-				throw new NotSupportedException(MessageFormat.format(JGitText.get().cannotReadFile, propsFile), e);
-			}
-		} else {
-			props = new Properties();
-			props.setProperty("accesskey", uri.getUser());
-			props.setProperty("secretkey", uri.getPass());
-		}
-
-		s3 = new AmazonS3(props);
+		s3 = new AmazonS3(loadProperties());
 		bucket = uri.getHost();
 
 		String p = uri.getPath();
@@ -153,6 +137,33 @@ public class TransportAmazonS3 extends HttpTransport implements WalkTransport {
 		keyPrefix = p;
 	}
 
+	private Properties loadProperties() throws NotSupportedException {
+		if (local.getDirectory() != null) {
+			File propsFile = new File(local.getDirectory(), uri.getUser());
+			if (propsFile.isFile())
+				return loadPropertiesFile(propsFile);
+		}
+
+		File propsFile = new File(local.getFS().userHome(), uri.getUser());
+		if (propsFile.isFile())
+			return loadPropertiesFile(propsFile);
+
+		Properties props = new Properties();
+		props.setProperty("accesskey", uri.getUser());
+		props.setProperty("secretkey", uri.getPass());
+		return props;
+	}
+
+	private static Properties loadPropertiesFile(File propsFile)
+			throws NotSupportedException {
+		try {
+			return AmazonS3.properties(propsFile);
+		} catch (IOException e) {
+			throw new NotSupportedException(MessageFormat.format(
+					JGitText.get().cannotReadFile, propsFile), e);
+		}
+	}
+
 	@Override
 	public FetchConnection openFetch() throws TransportException {
 		final DatabaseS3 c = new DatabaseS3(bucket, keyPrefix + "/objects");