rebase --apply: make reflog messages match rebase --merge

The apply backend creates slightly different reflog messages to the
merge backend when starting or finishing a rebase and when picking
commits. These differences make it harder than it needs to be to parse
the reflog (I have a script that reads the finishing messages from
rebase and it is a pain to have to accommodate two different message
formats). While it is possible to determine the backend used for a
rebase from the reflog messages, the differences are not designed for
that purpose. c2417d3 (rebase: drop '-i' from the reflog for
interactive-based rebases, 2020-02-15) removed the clear distinction
between the reflog messages of the two backends without complaint.

As the merge backend is the default it is likely to be the format most
common in existing reflogs. For that reason the apply backend is changed
to format its reflog messages to match the merge backend as closely as
possible. Note that there is still a difference as when committing a
conflict resolution the apply backend will use "(pick)" rather than
"(continue)" because it is not currently possible to change the message
for a single commit.

In addition to c2417d3 we also changed the reflog messages in
68aa495 (rebase: implement --merge via the interactive machinery,
2018-12-11) and 2ac0d62 (rebase: change the default backend from "am"
to "merge", 2020-02-15). This commit makes the same change to "git
rebase --apply" that 2ac0d62 made to "git rebase" without any backend
specific options. As the messages are changed to use an existing format
any scripts that can parse the reflog messages of the default rebase
backend should be unaffected by this change.

There are existing tests for the messages from both backends which are
adjusted to ensure that they do not get out of sync in the future.

Signed-off-by: Phillip Wood <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: phillipwood

builtin/rebase.c

@@ -582,10 +582,10 @@ static int move_to_original_branch(struct rebase_options *opts)
 	if (!opts->onto)
 		BUG("move_to_original_branch without onto");
 
-	strbuf_addf(&branch_reflog, "%s finished: %s onto %s",
+	strbuf_addf(&branch_reflog, "%s (finish): %s onto %s",
 		    getenv(GIT_REFLOG_ACTION_ENVIRONMENT),
 		    opts->head_name, oid_to_hex(&opts->onto->object.oid));
-	strbuf_addf(&head_reflog, "%s finished: returning to %s",
+	strbuf_addf(&head_reflog, "%s (finish): returning to %s",
 		    getenv(GIT_REFLOG_ACTION_ENVIRONMENT), opts->head_name);
 	ropts.branch = opts->head_name;
 	ropts.flags = RESET_HEAD_REFS_ONLY;
@@ -615,7 +615,8 @@ static int run_am(struct rebase_options *opts)
 
 	am.git_cmd = 1;
 	strvec_push(&am.args, "am");
-
+	strvec_pushf(&am.env, GIT_REFLOG_ACTION_ENVIRONMENT "=%s (pick)",
+		     getenv(GIT_REFLOG_ACTION_ENVIRONMENT));
 	if (opts->action && !strcmp("continue", opts->action)) {
 		strvec_push(&am.args, "--resolved");
 		strvec_pushf(&am.args, "--resolvemsg=%s", resolvemsg);
@@ -1792,7 +1793,7 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
 		printf(_("First, rewinding head to replay your work on top of "
 			 "it...\n"));
 
-	strbuf_addf(&msg, "%s: checkout %s",
+	strbuf_addf(&msg, "%s (start): checkout %s",
 		    getenv(GIT_REFLOG_ACTION_ENVIRONMENT), options.onto_name);
 	ropts.oid = &options.onto->object.oid;
 	ropts.orig_head = &options.orig_head->object.oid,

t/t3406-rebase-message.sh

@@ -88,7 +88,7 @@ test_expect_success 'error out early upon -C<n> or --whitespace=<bad>' '
 write_reflog_expect () {
 	if test $mode = --apply
 	then
-		sed 's/(finish)/finished/; s/ ([^)]*)//'
+		sed 's/(continue)/(pick)/'
 	else
 		cat
 	fi >expect