Merge branch 'en/am-abort-fix' into maint

When "git am --abort" fails to abort correctly, it still exited
with exit status of 0, which has been corrected.

* en/am-abort-fix:
  am: fix incorrect exit status on am fail to abort
  t4151: add a few am --abort tests
  git-am.txt: clarify --abort behavior

Author: gitster

Documentation/git-am.txt

@@ -178,6 +178,8 @@ default.   You can use `--no-utf8` to override this.
 
 --abort::
 	Restore the original branch and abort the patching operation.
+	Revert contents of files involved in the am operation to their
+	pre-am state.
 
 --quit::
 	Abort the patching operation but keep HEAD and the index

builtin/am.c

@@ -2106,7 +2106,8 @@ static void am_abort(struct am_state *state)
 	if (!has_orig_head)
 		oidcpy(&orig_head, the_hash_algo->empty_tree);
 
-	clean_index(&curr_head, &orig_head);
+	if (clean_index(&curr_head, &orig_head))
+		die(_("failed to clean index"));
 
 	if (has_orig_head)
 		update_ref("am --abort", "HEAD", &orig_head,

t/t4151-am-abort.sh

@@ -23,7 +23,13 @@ test_expect_success setup '
 		test_tick &&
 		git commit -a -m $i || return 1
 	done &&
+	git branch changes &&
 	git format-patch --no-numbered initial &&
+	git checkout -b conflicting initial &&
+	echo different >>file-1 &&
+	echo whatever >new-file &&
+	git add file-1 new-file &&
+	git commit -m different &&
 	git checkout -b side initial &&
 	echo local change >file-2-expect
 '
@@ -191,4 +197,37 @@ test_expect_success 'am --abort leaves index stat info alone' '
 	git diff-files --exit-code --quiet
 '
 
+test_expect_success 'git am --abort return failed exit status when it fails' '
+	test_when_finished "rm -rf file-2/ && git reset --hard && git am --abort" &&
+	git checkout changes &&
+	git format-patch -1 --stdout conflicting >changes.mbox &&
+	test_must_fail git am --3way changes.mbox &&
+
+	git rm file-2 &&
+	mkdir file-2 &&
+	echo precious >file-2/somefile &&
+	test_must_fail git am --abort &&
+	test_path_is_dir file-2/
+'
+
+test_expect_success 'git am --abort cleans relevant files' '
+	git checkout changes &&
+	git format-patch -1 --stdout conflicting >changes.mbox &&
+	test_must_fail git am --3way changes.mbox &&
+
+	test_path_is_file new-file &&
+	echo further changes >>file-1 &&
+	echo change other file >>file-2 &&
+
+	# Abort, and expect the files touched by am to be reverted
+	git am --abort &&
+
+	test_path_is_missing new-file &&
+
+	# Files not involved in am operation are left modified
+	git diff --name-only changes >actual &&
+	test_write_lines file-2 >expect &&
+	test_cmp expect actual
+'
+
 test_done