InvalidLongObjectIdException: Fix formatting of message

The message is formatted as:

  Invalid id: : abcde...

but should be:

  Invalid id: abcde...

Change-Id: Ie15cacdcf2f168edaee262e6cf8061ebfe9d998d
Signed-off-by: David Pursehouse <david.pursehouse@gmail.com>

org.eclipse.jgit.lfs.server.test/tst/org/eclipse/jgit/lfs/server/fs/DownloadTest.java

@@ -97,7 +97,7 @@ public class DownloadTest extends LfsServerTest {
 			getContent(id, f);
 			fail("expected RuntimeException");
 		} catch (RuntimeException e) {
-			String error = String.format("Invalid id: : %s", id);
+			String error = String.format("Invalid id: %s", id);
 			assertEquals(formatErrorMessage(SC_UNPROCESSABLE_ENTITY, error),
 					e.getMessage());
 		}

org.eclipse.jgit.lfs/src/org/eclipse/jgit/lfs/errors/InvalidLongObjectIdException.java

@@ -80,7 +80,7 @@ public class InvalidLongObjectIdException extends IllegalArgumentException {
 
 	private static String asAscii(byte[] bytes, int offset, int length) {
 		try {
-			return ": " + new String(bytes, offset, length, "US-ASCII"); //$NON-NLS-1$ //$NON-NLS-2$
+			return new String(bytes, offset, length, "US-ASCII"); //$NON-NLS-1$
 		} catch (UnsupportedEncodingException e2) {
 			return ""; //$NON-NLS-1$
 		} catch (StringIndexOutOfBoundsException e2) {