abspath_part_inside_repo: respect core.ignoreCase

If the file system is case-insensitive, we really must be careful to
ignore differences in case only.

This fixes https://github.com/git-for-windows/git/issues/735

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

setup.c

@@ -39,7 +39,7 @@ static int abspath_part_inside_repo(char *path)
 	off = offset_1st_component(path);
 
 	/* check if work tree is already the prefix */
-	if (wtlen <= len && !strncmp(path, work_tree, wtlen)) {
+	if (wtlen <= len && !fspathncmp(path, work_tree, wtlen)) {
 		if (path[wtlen] == '/') {
 			memmove(path, path + wtlen + 1, len - wtlen);
 			return 0;
@@ -59,7 +59,7 @@ static int abspath_part_inside_repo(char *path)
 		path++;
 		if (*path == '/') {
 			*path = '\0';
-			if (strcmp(real_path(path0), work_tree) == 0) {
+			if (fspathcmp(real_path(path0), work_tree) == 0) {
 				memmove(path0, path + 1, len - (path - path0));
 				return 0;
 			}
@@ -68,7 +68,7 @@ static int abspath_part_inside_repo(char *path)
 	}
 
 	/* check whole path */
-	if (strcmp(real_path(path0), work_tree) == 0) {
+	if (fspathcmp(real_path(path0), work_tree) == 0) {
 		*path0 = '\0';
 		return 0;
 	}

t/t3700-add.sh

@@ -402,4 +402,11 @@ test_expect_success 'all statuses changed in folder if . is given' '
 	test $(git ls-files --stage | grep ^100755 | wc -l) -eq 0
 '
 
+test_expect_success CASE_INSENSITIVE_FS 'path is case-insensitive' '
+	path="$(pwd)/BLUB" &&
+	touch "$path" &&
+	downcased="$(echo "$path" | tr A-Z a-z)" &&
+	git add "$downcased"
+'
+
 test_done