Post commit hook failure should not cause commit failure

As the post commit hook is run after a commit is finished, it can not
abort the commit and the exit code of this hook should not have any
effect.

This can be achieved by not throwing a AbortedByHookException exception.
The stderr output is not lost thanks to contributions for bug 553471.

Bug: 553428
Change-Id: I451a76e04103e632ff44e045561c5a41f7b7d558
Signed-off-by: Tim Neumann <Tim.Neumann@advantest.com>
Signed-off-by: Fabian Pfaff <fabian.pfaff@vogella.com>
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

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

@@ -170,13 +170,31 @@ public abstract class GitHook<T> implements Callable<T> {
 				getParameters(), getOutputStream(), stderrStream,
 				getStdinArgs());
 		if (result.isExecutedWithError()) {
-			throw new AbortedByHookException(
-					new String(errorByteArray.toByteArray(),
-							Charset.defaultCharset().name()),
-					getHookName(), result.getExitCode());
+			handleError(new String(errorByteArray.toByteArray(),
+					Charset.defaultCharset().name()), result);
 		}
 	}
 
+	/**
+	 * Process that the hook exited with an error. This default implementation
+	 * throws an {@link AbortedByHookException }. Hooks which need a different
+	 * behavior can overwrite this method.
+	 *
+	 * @param message
+	 *            error message
+	 * @param result
+	 *            The process result of the hook
+	 * @throws AbortedByHookException
+	 *             When the hook should be aborted
+	 * @since 5.11
+	 */
+	protected void handleError(String message,
+			final ProcessResult result)
+			throws AbortedByHookException {
+		throw new AbortedByHookException(message, getHookName(),
+				result.getExitCode());
+	}
+
 	/**
 	 * Check whether a 'native' (i.e. script) hook is installed in the
 	 * repository.

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

@@ -14,6 +14,7 @@ import java.io.PrintStream;
 
 import org.eclipse.jgit.api.errors.AbortedByHookException;
 import org.eclipse.jgit.lib.Repository;
+import org.eclipse.jgit.util.ProcessResult;
 
 /**
  * The <code>post-commit</code> hook implementation. This hook is run after the
@@ -73,4 +74,16 @@ public class PostCommitHook extends GitHook<Void> {
 		return NAME;
 	}
 
+
+	/**
+	 * Overwrites the default implementation to never throw an
+	 * {@link AbortedByHookException}, as the commit has already been done and
+	 * the exit code of the post-commit hook has no effect.
+	 */
+	@Override
+	protected void handleError(String message, ProcessResult result)
+			throws AbortedByHookException {
+		// Do nothing as the exit code of the post-commit hook has no effect.
+	}
+
 }