t9103: modernize test style

The main goal here was to avoid double-quotes for
surrounding the test snippet, since it makes the code hard
to read (and to grep for common problems).

But while we're here, we can fix a few other things:

  - use test_path_* helpers, which are more robust and give
    better error messages

  - only "cd" inside a subshell, which leaves the
    environment pristine if further tests are added

  - consistently quote shell arguments. These aren't wrong
    if we assume find-rev output doesn't have any
    whitespace, but it doesn't hurt to be careful.

  - replace the old-style 'test x$foo = x' with 'test -z
    "$foo"'. Besides the quoting fix, this is the form we
    generally use in our test suite.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t9103-git-svn-tracked-directory-removed.sh

@@ -23,17 +23,19 @@ test_expect_success 'make history for tracking' '
 
 test_expect_success 'clone repo with git' '
 	git svn clone -s "$svnrepo" x &&
-	test -f x/FOLLOWME &&
+	test_path_is_file x/FOLLOWME &&
-	test ! -f x/README
+	test_path_is_missing x/README
 '
 
-test_expect_success 'make sure r2 still has old file' "
+test_expect_success 'make sure r2 still has old file' '
+	(
 		cd x &&
-		test -n \"\$(git svn find-rev r1)\" &&
+		test -n "$(git svn find-rev r1)" &&
-		git reset --hard \$(git svn find-rev r1) &&
+		git reset --hard "$(git svn find-rev r1)" &&
-		test -f README &&
+		test_path_is_file README &&
-		test ! -f FOLLOWME &&
+		test_path_is_missing FOLLOWME &&
-		test x\$(git svn find-rev r2) = x
+		test -z "$(git svn find-rev r2)"
-"
+	)
+'
 
 test_done