Throw URISyntaxException for incorrect percent-encoding

URIish.unescape() threw an ArrayIndexOutOfBoundsException if the given
url has incorrect percent-encoding (e.g. http://example.com/%gg). But an
URISyntaxException is much better to know the reason of the failure.

Change-Id: I3f40a26d43cd2eb4e32c11aba7dc2594bc1f98e2
Signed-off-by: Yi EungJun <eungjun.yi@navercorp.com>

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

@@ -252,6 +252,11 @@ public class URIish implements Serializable {
 		throw new URISyntaxException(s, JGitText.get().cannotParseGitURIish);
 	}
 
+	private static int parseHexByte(byte c1, byte c2) {
+			return ((RawParseUtils.parseHexInt4(c1) << 4)
+					| RawParseUtils.parseHexInt4(c2));
+	}
+
 	private static String unescape(String s) throws URISyntaxException {
 		if (s == null)
 			return null;
@@ -272,8 +277,14 @@ public class URIish implements Serializable {
 			if (c == '%') {
 				if (i + 2 >= bytes.length)
 					throw new URISyntaxException(s, JGitText.get().cannotParseGitURIish);
-				int val = (RawParseUtils.parseHexInt4(bytes[i + 1]) << 4)
-						| RawParseUtils.parseHexInt4(bytes[i + 2]);
+				byte c1 = bytes[i + 1];
+				byte c2 = bytes[i + 2];
+				int val;
+				try {
+					val = parseHexByte(c1, c2);
+				} catch (ArrayIndexOutOfBoundsException e) {
+					throw new URISyntaxException(s, JGitText.get().cannotParseGitURIish);
+				}
 				os[j++] = (byte) val;
 				i += 2;
 			} else