rebase: deprecate --preserve-merges

We have something much better now: --rebase-merges (which is a
complete re-design --preserve-merges, with a lot of issues fixed such as
the inability to reorder commits with --preserve-merges).

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

Documentation/config/branch.txt

@@ -85,9 +85,9 @@ 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'.
+When `preserve` (deprecated in favor of `merges`), also pass
+`--preserve-merges` along to 'git rebase' so that locally committed merge
+commits will not be flattened by running 'git pull'.
 +
 When the value is `interactive`, the rebase is run in interactive mode.
 +

Documentation/config/pull.txt

@@ -18,9 +18,9 @@ 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'.
+When `preserve` (deprecated in favor of `merges`), also pass
+`--preserve-merges` along to 'git rebase' so that locally committed merge
+commits will not be flattened by running 'git pull'.
 +
 When the value is `interactive`, the rebase is run in interactive mode.
 +

Documentation/git-rebase.txt

@@ -415,9 +415,9 @@ i.e. commits that would be excluded by gitlink:git-log[1]'s
 the `rebase-cousins` mode is turned on, such commits are instead rebased
 onto `<upstream>` (or `<onto>`, if specified).
 +
-The `--rebase-merges` mode is similar in spirit to `--preserve-merges`, but
-in contrast to that option works well in interactive rebases: commits can be
-reordered, inserted and dropped at will.
+The `--rebase-merges` mode is similar in spirit to the deprecated
+`--preserve-merges`, but in contrast to that option works well in interactive
+rebases: commits can be reordered, inserted and dropped at will.
 +
 It is currently only possible to recreate the merge commits using the
 `recursive` merge strategy; Different merge strategies can be used only via
@@ -427,9 +427,10 @@ See also REBASING MERGES and INCOMPATIBLE OPTIONS below.
 
 -p::
 --preserve-merges::
-	Recreate merge commits instead of flattening the history by replaying
-	commits a merge commit introduces. Merge conflict resolutions or manual
-	amendments to merge commits are not preserved.
+	[DEPRECATED: use `--rebase-merges` instead] Recreate merge commits
+	instead of flattening the history by replaying commits a merge commit
+	introduces. Merge conflict resolutions or manual amendments to merge
+	commits are not preserved.
 +
 This uses the `--interactive` machinery internally, but combining it
 with the `--interactive` option explicitly is generally not a good
@@ -1020,11 +1021,11 @@ merge cmake
 
 BUGS
 ----
-The todo list presented by `--preserve-merges --interactive` does not
-represent the topology of the revision graph.  Editing commits and
-rewording their commit messages should work fine, but attempts to
-reorder commits tend to produce counterintuitive results. Use
-`--rebase-merges` in such scenarios instead.
+The todo list presented by the deprecated `--preserve-merges --interactive`
+does not represent the topology of the revision graph (use `--rebase-merges`
+instead).  Editing commits and rewording their commit messages should work
+fine, but attempts to reorder commits tend to produce counterintuitive results.
+Use `--rebase-merges` in such scenarios instead.
 
 For example, an attempt to rearrange
 ------------

builtin/rebase.c

@@ -1100,8 +1100,8 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
 			PARSE_OPT_NOARG | PARSE_OPT_NONEG,
 			parse_opt_interactive },
 		OPT_SET_INT('p', "preserve-merges", &options.type,
-			    N_("try to recreate merges instead of ignoring "
-			       "them"), REBASE_PRESERVE_MERGES),
+			    N_("(DEPRECATED) try to recreate merges instead of "
+			       "ignoring them"), REBASE_PRESERVE_MERGES),
 		OPT_BOOL(0, "rerere-autoupdate",
 			 &options.allow_rerere_autoupdate,
 			 N_("allow rerere to update index with resolved "
@@ -1212,6 +1212,10 @@ int cmd_rebase(int argc, const char **argv, const char *prefix)
 		usage_with_options(builtin_rebase_usage,
 				   builtin_rebase_options);
 
+	if (options.type == REBASE_PRESERVE_MERGES)
+		warning(_("git rebase --preserve-merges is deprecated. "
+			  "Use --rebase-merges instead."));
+
 	if (action != NO_ACTION && !in_progress)
 		die(_("No rebase in progress?"));
 	setenv(GIT_REFLOG_ACTION_ENVIRONMENT, "rebase", 0);