Revert "Merge branch 'en/merge-recursive'"

As the band-aid to merge-recursive seems to regress complex merges in an
unpleasant way.  The merge-recursive implementation needs to be rewritten
in such a way that it resolves renames and D/F conflicts entirely in-core
and not to touch working tree at all while doing so. But in the meantime,
this reverts commit ac9666f84 that merged the topic in its entirety.

merge-recursive.c

@@ -341,11 +341,10 @@ static void make_room_for_directories_of_df_conflicts(struct merge_options *o,
 	 * make room for the corresponding directory.  Such paths will
 	 * later be processed in process_df_entry() at the end.  If
 	 * the corresponding directory ends up being removed by the
-	 * merge, then the file will be reinstated at that time
-	 * (albeit with a different timestamp!); otherwise, if the
-	 * file is not supposed to be removed by the merge, the
-	 * contents of the file will be placed in another unique
-	 * filename.
+	 * merge, then the file will be reinstated at that time;
+	 * otherwise, if the file is not supposed to be removed by the
+	 * merge, the contents of the file will be placed in another
+	 * unique filename.
 	 *
 	 * NOTE: This function relies on the fact that entries for a
 	 * D/F conflict will appear adjacent in the index, with the
@@ -356,13 +355,6 @@ static void make_room_for_directories_of_df_conflicts(struct merge_options *o,
 	int last_len = 0;
 	int i;
 
-	/*
-	 * Do not do any of this crazyness during the recursive; we don't
-	 * even write anything to the working tree!
-	 */
-	if (o->call_depth)
-		return;
-
 	for (i = 0; i < entries->nr; i++) {
 		const char *path = entries->items[i].string;
 		int len = strlen(path);
@@ -1265,13 +1257,9 @@ static int merge_content(struct merge_options *o,
 	}
 
 	if (mfi.clean && !df_conflict_remains &&
-	    sha_eq(mfi.sha, a_sha) && mfi.mode == a.mode &&
-	    !o->call_depth && !lstat(path, &st)) {
+	    sha_eq(mfi.sha, a_sha) && mfi.mode == a.mode)
 		output(o, 3, "Skipped %s (merged same as existing)", path);
-		add_cacheinfo(mfi.mode, mfi.sha, path,
-			      0 /*stage*/, 1 /*refresh*/, 0 /*options*/);
-		return mfi.clean;
-	} else
+	else
 		output(o, 2, "Auto-merging %s", path);
 
 	if (!mfi.clean) {

t/t6022-merge-rename.sh

@@ -609,67 +609,4 @@ test_expect_success 'check handling of differently renamed file with D/F conflic
 	! test -f original
 '
 
-test_expect_success 'setup avoid unnecessary update, normal rename' '
-	git reset --hard &&
-	git checkout --orphan avoid-unnecessary-update-1 &&
-	git rm -rf . &&
-	git clean -fdqx &&
-
-	printf "1\n2\n3\n4\n5\n6\n7\n8\n9\n10\n" >original &&
-	git add -A &&
-	git commit -m "Common commmit" &&
-
-	git mv original rename &&
-	echo 11 >>rename &&
-	git add -u &&
-	git commit -m "Renamed and modified" &&
-
-	git checkout -b merge-branch-1 HEAD~1 &&
-	echo "random content" >random-file &&
-	git add -A &&
-	git commit -m "Random, unrelated changes"
-'
-
-test_expect_success 'avoid unnecessary update, normal rename' '
-	git checkout -q avoid-unnecessary-update-1^0 &&
-	test-chmtime =1000000000 rename &&
-	test-chmtime -v +0 rename >expect &&
-	git merge merge-branch-1 &&
-	test-chmtime -v +0 rename >actual &&
-	test_cmp expect actual # "rename" should have stayed intact
-'
-
-test_expect_success 'setup to test avoiding unnecessary update, with D/F conflict' '
-	git reset --hard &&
-	git checkout --orphan avoid-unnecessary-update-2 &&
-	git rm -rf . &&
-	git clean -fdqx &&
-
-	mkdir df &&
-	printf "1\n2\n3\n4\n5\n6\n7\n8\n9\n10\n" >df/file &&
-	git add -A &&
-	git commit -m "Common commmit" &&
-
-	git mv df/file temp &&
-	rm -rf df &&
-	git mv temp df &&
-	echo 11 >>df &&
-	git add -u &&
-	git commit -m "Renamed and modified" &&
-
-	git checkout -b merge-branch-2 HEAD~1 &&
-	>unrelated-change &&
-	git add unrelated-change &&
-	git commit -m "Only unrelated changes"
-'
-
-test_expect_failure 'avoid unnecessary update, with D/F conflict' '
-	git checkout -q avoid-unnecessary-update-2^0 &&
-	test-chmtime =1000000000 df &&
-	test-chmtime -v +0 df >expect &&
-	git merge merge-branch-2 &&
-	test-chmtime -v +0 df >actual &&
-	test_cmp expect actual # "df" should have stayed intact
-'
-
 test_done