Merge branch 'dt/merge-recursive-case-insensitive' into maint

On a case insensitive filesystem, merge-recursive incorrectly
deleted the file that is to be renamed to a name that is the same
except for case differences.

* dt/merge-recursive-case-insensitive:
  mv: allow renaming to fix case on case insensitive filesystems
  merge-recursive.c: fix case-changing merge bug

builtin/mv.c

@@ -203,7 +203,8 @@ int cmd_mv(int argc, const char **argv, const char *prefix)
 			}
 		} else if (cache_name_pos(src, length) < 0)
 			bad = _("not under version control");
-		else if (lstat(dst, &st) == 0) {
+		else if (lstat(dst, &st) == 0 &&
+			 (!ignore_case || strcasecmp(src, dst))) {
 			bad = _("destination exists");
 			if (force) {
 				/*

merge-recursive.c

@@ -589,6 +589,12 @@ static int remove_file(struct merge_options *o, int clean,
 			return -1;
 	}
 	if (update_working_directory) {
+		if (ignore_case) {
+			struct cache_entry *ce;
+			ce = cache_file_exists(path, strlen(path), ignore_case);
+			if (ce && ce_stage(ce) == 0)
+				return 0;
+		}
 		if (remove_path(path))
 			return -1;
 	}

t/t6039-merge-ignorecase.sh

@@ -0,0 +1,53 @@
+#!/bin/sh
+
+test_description='git-merge with case-changing rename on case-insensitive file system'
+
+. ./test-lib.sh
+
+if ! test_have_prereq CASE_INSENSITIVE_FS
+then
+	skip_all='skipping case insensitive tests - case sensitive file system'
+	test_done
+fi
+
+test_expect_success 'merge with case-changing rename' '
+	test $(git config core.ignorecase) = true &&
+	>TestCase &&
+	git add TestCase &&
+	git commit -m "add TestCase" &&
+	git tag baseline
+	git checkout -b with-camel &&
+	>foo &&
+	git add foo &&
+	git commit -m "intervening commit" &&
+	git checkout master &&
+	git rm TestCase &&
+	>testcase &&
+	git add testcase &&
+	git commit -m "rename to testcase" &&
+	git checkout with-camel &&
+	git merge master -m "merge" &&
+	test_path_is_file testcase
+'
+
+test_expect_success 'merge with case-changing rename on both sides' '
+	git checkout master &&
+	git reset --hard baseline &&
+	git branch -D with-camel &&
+	git checkout -b with-camel &&
+	git mv TestCase testcase &&
+	git commit -m "recase on branch" &&
+	>foo &&
+	git add foo &&
+	git commit -m "intervening commit" &&
+	git checkout master &&
+	git rm TestCase &&
+	>testcase &&
+	git add testcase &&
+	git commit -m "rename to testcase" &&
+	git checkout with-camel &&
+	git merge master -m "merge" &&
+	test_path_is_file testcase
+'
+
+test_done