Merge branch 'jk/startup-info' into maint

The startup_info data, which records if we are working inside a
repository (among other things), are now uniformly available to Git
subcommand implementations, and Git avoids attempting to touch
references when we are not in a repository.

* jk/startup-info:
  use setup_git_directory() in test-* programs
  grep: turn off gitlink detection for --no-index
  mailmap: do not resolve blobs in a non-repository
  remote: don't resolve HEAD in non-repository
  setup: set startup_info->have_repository more reliably
  setup: make startup_info available everywhere

t/t1506-rev-parse-diagnosis.sh

@@ -166,11 +166,6 @@ test_expect_success 'relative path when cwd is outside worktree' '
 	grep "relative path syntax can.t be used outside working tree." error
 '
 
-test_expect_success 'relative path when startup_info is NULL' '
-	test_must_fail test-match-trees HEAD:./file.txt HEAD:./file.txt 2>error &&
-	grep "BUG: startup_info struct is not initialized." error
-'
-
 test_expect_success '<commit>:file correctly diagnosed after a pathname' '
 	test_must_fail git rev-parse file.txt HEAD:file.txt 1>actual 2>error &&
 	test_i18ngrep ! "exists on disk" error &&

t/t7810-grep.sh

@@ -905,6 +905,33 @@ test_expect_success 'inside git repository but with --no-index' '
 	)
 '
 
+test_expect_success 'grep --no-index descends into repos, but not .git' '
+	rm -fr non &&
+	mkdir -p non/git &&
+	(
+		GIT_CEILING_DIRECTORIES="$(pwd)/non" &&
+		export GIT_CEILING_DIRECTORIES &&
+		cd non/git &&
+
+		echo magic >file &&
+		git init repo &&
+		(
+			cd repo &&
+			echo magic >file &&
+			git add file &&
+			git commit -m foo &&
+			echo magic >.git/file
+		) &&
+
+		cat >expect <<-\EOF &&
+		file
+		repo/file
+		EOF
+		git grep -l --no-index magic >actual &&
+		test_cmp expect actual
+	)
+'
+
 test_expect_success 'setup double-dash tests' '
 cat >double-dash <<EOF &&
 --