Rebase Interoperability first part: write "interactive" file

The Repository is then in state "Rebase interactive".

Change-Id: I5d2de57f8670e1d4c71ed22509ab17f04e2561b5
Signed-off-by: Mathias Kinzler <mathias.kinzler@sap.com>

org.eclipse.jgit.test/tst/org/eclipse/jgit/api/RebaseCommandTest.java

@@ -322,7 +322,8 @@ public class RebaseCommandTest extends RepositoryTestCase {
 		checkFile(theFile,
 				"<<<<<<< OURS\n1master\n=======\n1topic\n>>>>>>> THEIRS\n2\n3\ntopic4\n");
 
-		assertEquals(RepositoryState.REBASING_MERGE, db.getRepositoryState());
+		assertEquals(RepositoryState.REBASING_INTERACTIVE, db
+				.getRepositoryState());
 		assertTrue(new File(db.getDirectory(), "rebase-merge").exists());
 		// the first one should be included, so we should have left two picks in
 		// the file
@@ -410,7 +411,8 @@ public class RebaseCommandTest extends RepositoryTestCase {
 		assertEquals(Status.STOPPED, res.getStatus());
 		assertEquals(conflicting, res.getCurrentCommit());
 
-		assertEquals(RepositoryState.REBASING_MERGE, db.getRepositoryState());
+		assertEquals(RepositoryState.REBASING_INTERACTIVE, db
+				.getRepositoryState());
 		assertTrue(new File(db.getDirectory(), "rebase-merge").exists());
 		// the first one should be included, so we should have left two picks in
 		// the file

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

@@ -325,6 +325,7 @@ public class RebaseCommand extends GitCommand<RebaseResult> {
 		createFile(rebaseDir, "head", headId.name());
 		createFile(rebaseDir, "head-name", headName);
 		createFile(rebaseDir, "onto", upstreamCommit.name());
+		createFile(rebaseDir, "interactive", "");
 		BufferedWriter fw = new BufferedWriter(new OutputStreamWriter(
 				new FileOutputStream(new File(rebaseDir, "git-rebase-todo")),
 				"UTF-8"));