Fix IndexOutOfBoundsException when parsing PersonIdent

IndexOutOfBoundsException could occur when parsing
PersonIdent for which no name is present, as part of a
RevCommit (nameB > 0).

org.eclipse.jgit.test/tst/org/eclipse/jgit/revwalk/RevCommitParseTest.java

@@ -161,6 +161,21 @@ public class RevCommitParseTest extends RepositoryTestCase {
 		assertEquals("", c.getShortMessage());
 	}
 
+	@Test
+	public void testParse_incompleteAuthorAndCommitter() throws Exception {
+		final StringBuilder b = new StringBuilder();
+		b.append("tree 9788669ad918b6fcce64af8882fc9a81cb6aba67\n");
+		b.append("author <a_u_thor@example.com> 1218123387 +0700\n");
+		b.append("committer <> 1218123390 -0500\n");
+
+		final RevCommit c;
+		c = new RevCommit(id("9473095c4cb2f12aefe1db8a355fe3fafba42f67"));
+		c.parseCanonical(new RevWalk(db), b.toString().getBytes("UTF-8"));
+
+		assertEquals(new PersonIdent("", "a_u_thor@example.com", 1218123387000l, 7), c.getAuthorIdent());
+		assertEquals(new PersonIdent("", "", 1218123390000l, -5), c.getCommitterIdent());
+	}
+
 	@Test
 	public void testParse_implicit_UTF8_encoded() throws Exception {
 		final ByteArrayOutputStream b = new ByteArrayOutputStream();

org.eclipse.jgit/src/org/eclipse/jgit/util/RawParseUtils.java

@@ -717,8 +717,8 @@ public final class RawParseUtils {
 				(emailE >= raw.length - 1 && raw[emailE - 1] != '>'))
 			return null;
 
-		final int nameEnd = emailB - 2 >= 0 && raw[emailB - 2] == ' ' ? emailB - 2
-				: emailB - 1;
+		final int nameEnd = emailB - 2 >= nameB && raw[emailB - 2] == ' ' ?
+				emailB - 2 : emailB - 1;
 		final String name = decode(cs, raw, nameB, nameEnd);
 		final String email = decode(cs, raw, emailB, emailE - 1);