pull: accept --rebase=merges to recreate the branch topology

Similar to the `preserve` mode simply passing the `--preserve-merges`
option to the `rebase` command, the `merges` mode simply passes the
`--rebase-merges` option.

This will allow users to conveniently rebase non-trivial commit
topologies when pulling new commits, without flattening them.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/config.txt

@@ -1058,6 +1058,10 @@ branch.<name>.rebase::
 	"git pull" is run. See "pull.rebase" for doing this in a non
 	branch-specific manner.
 +
+When `merges`, pass the `--rebase-merges` option to 'git rebase'
+so that the local merge commits are included in the rebase (see
+linkgit:git-rebase[1] for details).
++
 When preserve, also pass `--preserve-merges` along to 'git rebase'
 so that locally committed merge commits will not be flattened
 by running 'git pull'.
@@ -2617,6 +2621,10 @@ pull.rebase::
 	pull" is run. See "branch.<name>.rebase" for setting this on a
 	per-branch basis.
 +
+When `merges`, pass the `--rebase-merges` option to 'git rebase'
+so that the local merge commits are included in the rebase (see
+linkgit:git-rebase[1] for details).
++
 When preserve, also pass `--preserve-merges` along to 'git rebase'
 so that locally committed merge commits will not be flattened
 by running 'git pull'.

Documentation/git-pull.txt

@@ -101,13 +101,17 @@ Options related to merging
 include::merge-options.txt[]
 
 -r::
---rebase[=false|true|preserve|interactive]::
+--rebase[=false|true|merges|preserve|interactive]::
 	When true, rebase the current branch on top of the upstream
 	branch after fetching. If there is a remote-tracking branch
 	corresponding to the upstream branch and the upstream branch
 	was rebased since last fetched, the rebase uses that information
 	to avoid rebasing non-local changes.
 +
+When set to `merges`, rebase using `git rebase --rebase-merges` so that
+the local merge commits are included in the rebase (see
+linkgit:git-rebase[1] for details).
++
 When set to preserve, rebase with the `--preserve-merges` option passed
 to `git rebase` so that locally created merge commits will not be flattened.
 +

builtin/pull.c

@@ -27,14 +27,16 @@ enum rebase_type {
 	REBASE_FALSE = 0,
 	REBASE_TRUE,
 	REBASE_PRESERVE,
+	REBASE_MERGES,
 	REBASE_INTERACTIVE
 };
 
 /**
  * Parses the value of --rebase. If value is a false value, returns
  * REBASE_FALSE. If value is a true value, returns REBASE_TRUE. If value is
- * "preserve", returns REBASE_PRESERVE. If value is a invalid value, dies with
- * a fatal error if fatal is true, otherwise returns REBASE_INVALID.
+ * "merges", returns REBASE_MERGES. If value is "preserve", returns
+ * REBASE_PRESERVE. If value is a invalid value, dies with a fatal error if
+ * fatal is true, otherwise returns REBASE_INVALID.
  */
 static enum rebase_type parse_config_rebase(const char *key, const char *value,
 		int fatal)
@@ -47,6 +49,8 @@ static enum rebase_type parse_config_rebase(const char *key, const char *value,
 		return REBASE_TRUE;
 	else if (!strcmp(value, "preserve"))
 		return REBASE_PRESERVE;
+	else if (!strcmp(value, "merges"))
+		return REBASE_MERGES;
 	else if (!strcmp(value, "interactive"))
 		return REBASE_INTERACTIVE;
 
@@ -130,7 +134,7 @@ static struct option pull_options[] = {
 	/* Options passed to git-merge or git-rebase */
 	OPT_GROUP(N_("Options related to merging")),
 	{ OPTION_CALLBACK, 'r', "rebase", &opt_rebase,
-	  "false|true|preserve|interactive",
+	  "false|true|merges|preserve|interactive",
 	  N_("incorporate changes by rebasing rather than merging"),
 	  PARSE_OPT_OPTARG, parse_opt_rebase },
 	OPT_PASSTHRU('n', NULL, &opt_diffstat, NULL,
@@ -800,7 +804,9 @@ static int run_rebase(const struct object_id *curr_head,
 	argv_push_verbosity(&args);
 
 	/* Options passed to git-rebase */
-	if (opt_rebase == REBASE_PRESERVE)
+	if (opt_rebase == REBASE_MERGES)
+		argv_array_push(&args, "--rebase-merges");
+	else if (opt_rebase == REBASE_PRESERVE)
 		argv_array_push(&args, "--preserve-merges");
 	else if (opt_rebase == REBASE_INTERACTIVE)
 		argv_array_push(&args, "--interactive");

builtin/remote.c

@@ -245,7 +245,9 @@ static int add(int argc, const char **argv)
 struct branch_info {
 	char *remote_name;
 	struct string_list merge;
-	enum { NO_REBASE, NORMAL_REBASE, INTERACTIVE_REBASE } rebase;
+	enum {
+		NO_REBASE, NORMAL_REBASE, INTERACTIVE_REBASE, REBASE_MERGES
+	} rebase;
 };
 
 static struct string_list branch_list = STRING_LIST_INIT_NODUP;
@@ -306,6 +308,8 @@ static int config_read_branches(const char *key, const char *value, void *cb)
 				info->rebase = v;
 			else if (!strcmp(value, "preserve"))
 				info->rebase = NORMAL_REBASE;
+			else if (!strcmp(value, "merges"))
+				info->rebase = REBASE_MERGES;
 			else if (!strcmp(value, "interactive"))
 				info->rebase = INTERACTIVE_REBASE;
 		}
@@ -963,9 +967,15 @@ static int show_local_info_item(struct string_list_item *item, void *cb_data)
 
 	printf("    %-*s ", show_info->width, item->string);
 	if (branch_info->rebase) {
-		printf_ln(branch_info->rebase == INTERACTIVE_REBASE
-			  ? _("rebases interactively onto remote %s")
-			  : _("rebases onto remote %s"), merge->items[0].string);
+		const char *msg;
+		if (branch_info->rebase == INTERACTIVE_REBASE)
+			msg = _("rebases interactively onto remote %s");
+		else if (branch_info->rebase == REBASE_MERGES)
+			msg = _("rebases interactively (with merges) onto "
+				"remote %s");
+		else
+			msg = _("rebases onto remote %s");
+		printf_ln(msg, merge->items[0].string);
 		return 0;
 	} else if (show_info->any_rebase) {
 		printf_ln(_(" merges with remote %s"), merge->items[0].string);

contrib/completion/git-completion.bash

@@ -2115,7 +2115,7 @@ _git_config ()
 		return
 		;;
 	branch.*.rebase)
-		__gitcomp "false true preserve interactive"
+		__gitcomp "false true merges preserve interactive"
 		return
 		;;
 	remote.pushdefault)