Add RepositoryState.BARE

A bare repository cannot be checked out, committed to, etc. as it
doesn't have a working directory.  Define this as a state since the
state enumeration exists only to describe how a working directory
can be modified.

Change-Id: I0a299013c6e42fef6cae3f6a9446f8f6c8e0514a
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

org.eclipse.jgit/src/org/eclipse/jgit/lib/Repository.java

@@ -1188,6 +1188,9 @@ public class Repository {
 	 * @return an important state
 	 */
 	public RepositoryState getRepositoryState() {
+		if (isBare())
+			return RepositoryState.BARE;
+
 		// Pre Git-1.6 logic
 		if (new File(getWorkDir(), ".dotest").exists())
 			return RepositoryState.REBASING;

org.eclipse.jgit/src/org/eclipse/jgit/lib/RepositoryState.java

@@ -54,6 +54,14 @@ package org.eclipse.jgit.lib;
  * on the state are the only supported means of deciding what to do.
  */
 public enum RepositoryState {
+	/** Has no work tree and cannot be used for normal editing. */
+	BARE {
+		public boolean canCheckout() { return false; }
+		public boolean canResetHead() { return false; }
+		public boolean canCommit() { return false; }
+		public String getDescription() { return "Bare"; }
+	},
+
 	/**
 	 * A safe state for working normally
 	 * */