GitHook: use default charset for output and error streams

External scripts most probably expect the default charset.

Change-Id: I318a5e1d9f536a95e70c06ffb5b6f408cd40f73a
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

org.eclipse.jgit/src/org/eclipse/jgit/hooks/GitHook.java

  */
 package org.eclipse.jgit.hooks;
 
-import static java.nio.charset.StandardCharsets.UTF_8;
-
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.io.OutputStream;
+import java.nio.charset.Charset;
 import java.util.concurrent.Callable;
 
 import org.eclipse.jgit.api.errors.AbortedByHookException;
 	 *
 	 * @throws org.eclipse.jgit.api.errors.AbortedByHookException
 	 *             If the underlying hook script exited with non-zero.
+	 * @throws IOException
+	 *             if an IO error occurred
 	 */
-	protected void doRun() throws AbortedByHookException {
+	protected void doRun() throws AbortedByHookException, IOException {
 		final ByteArrayOutputStream errorByteArray = new ByteArrayOutputStream();
 		final TeeOutputStream stderrStream = new TeeOutputStream(errorByteArray,
 				getErrorStream());
 				getStdinArgs());
 		if (result.isExecutedWithError()) {
 			throw new AbortedByHookException(
-					new String(errorByteArray.toByteArray(), UTF_8),
+					new String(errorByteArray.toByteArray(),
+							Charset.defaultCharset().name()),
 					getHookName(), result.getExitCode());
 		}
 	}