sparse: add vfs-specific precautions

* t1092: remove the 'git update-index' test that currently fails
  because the command ignores the bad path, but doesn't return a
  failure.

* dir.c: prevent matching against sparse-checkout patterns when the
  virtual filesystem is enabled. Should prevent some corner case
  issues.

* t1092: add quiet mode for some rebase tests because the stderr
  output can change in some of the modes.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>

Author: derrickstolee

Diff for: dir.c

@@ -1583,6 +1583,13 @@ static int path_in_sparse_checkout_1(const char *path,
 	enum pattern_match_result match = UNDECIDED;
 	const char *end, *slash;
 
+	/*
+	 * When using a virtual filesystem, there aren't really patterns
+	 * to follow, but be extra careful to skip this check.
+	 */
+	if (core_virtualfilesystem)
+		return 1;
+
 	/*
 	 * We default to accepting a path if the path is empty, there are no
 	 * patterns, or the patterns are of the wrong type.

Diff for: t/t1092-sparse-checkout-compatibility.sh

@@ -1060,7 +1060,9 @@ test_expect_success 'read-tree --merge with directory-file conflicts' '
 test_expect_success 'merge, cherry-pick, and rebase' '
 	init_repos &&
 
-	for OPERATION in "merge -m merge" cherry-pick "rebase --apply" "rebase --merge"
+	# microsoft/git specific: we need to use "quiet" mode
+	# to avoid different stderr for some rebases.
+	for OPERATION in "merge -m merge" cherry-pick "rebase -q --apply" "rebase -q --merge"
 	do
 		test_all_match git checkout -B temp update-deep &&
 		test_all_match git $OPERATION update-folder1 &&