Fix NPE in TransportGitSsh.ExtSession.exec()

Bug: 527383
Change-Id: I965860b4e0e9aa1adf6a1bb0735940cbd22adced
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

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

@@ -242,14 +242,7 @@ public class TransportGitSsh extends SshTransport implements PackTransport {
 				args.add(getURI().getHost());
 			args.add(command);
 
-			ProcessBuilder pb = new ProcessBuilder();
-			pb.command(args);
-
-			File directory = local.getDirectory();
-			if (directory != null)
-				pb.environment().put(Constants.GIT_DIR_KEY,
-						directory.getPath());
-
+			ProcessBuilder pb = createProcess(args);
 			try {
 				return pb.start();
 			} catch (IOException err) {
@@ -257,6 +250,17 @@ public class TransportGitSsh extends SshTransport implements PackTransport {
 			}
 		}
 
+		private ProcessBuilder createProcess(List<String> args) {
+			ProcessBuilder pb = new ProcessBuilder();
+			pb.command(args);
+			File directory = local != null ? local.getDirectory() : null;
+			if (directory != null) {
+				pb.environment().put(Constants.GIT_DIR_KEY,
+						directory.getPath());
+			}
+			return pb;
+		}
+
 		@Override
 		public void disconnect() {
 			// Nothing to do