Add a test for parsing fsck config options and expose FsckMode enum

These config options allow overriding the message type (error, warn or
ignore) of a specific message ID such as missingEmail.
The supported fsck message IDs are defined in ObjectChecker.ErrorType.

Since TransferConfig.FsckMode wasn't public parsing fsck configuration
options like e.g. fsck.missingEmail=ignore failed with an
IllegalAccessException. Fix this by declaring this enum public.

Change-Id: I3f41ff7a76a846250a63ce92a9fd111eb347269f
Signed-off-by: David Turner <dturner@twosigma.com>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

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

@@ -83,6 +83,11 @@ public class PushCommandTest extends RepositoryTestCase {
 
 		// create other repository
 		Repository db2 = createWorkRepository();
+		final StoredConfig config2 = db2.getConfig();
+
+		// this tests that this config can be parsed properly
+		config2.setString("fsck", "", "missingEmail", "ignore");
+		config2.save();
 
 		// setup the first repository
 		final StoredConfig config = db.getConfig();

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

@@ -76,8 +76,24 @@ public class TransferConfig {
 		}
 	};
 
-	enum FsckMode {
-		ERROR, WARN, IGNORE;
+	/**
+	 * A git configuration value for how to handle a fsck failure of a particular kind.
+	 * Used in e.g. fsck.missingEmail.
+	 * @since 4.9
+	 */
+	public enum FsckMode {
+		/**
+		 * Treat it as an error (the default).
+		 */
+		ERROR,
+		/**
+		 * Issue a warning (in fact, jgit treats this like IGNORE, but git itself does warn).
+		 */
+		WARN,
+		/**
+		 * Ignore the error.
+		 */
+		IGNORE;
 	}
 
 	private final boolean fetchFsck;