Revert "Merge branch 'ps/validate-prefix-in-subtree-split' into next"

This reverts commit 70c03b7, reversing
changes made to faf2e08, as it is
reported that subtree tests (in contrib/) are broken by this change.

https://lore.kernel.org/git/7k7ewvrb5hj3jyesiigy6dvo5w5pl67rk7ihztsuxbtqpymafv@ey64nvhzhacg/

Author: gitster

contrib/subtree/git-subtree.sh

@@ -257,9 +257,6 @@ main () {
 		test -e "$arg_prefix" &&
 			die "fatal: prefix '$arg_prefix' already exists."
 		;;
-	split)
-		# checked later against the commit, not the working tree
-		;;
 	*)
 		test -e "$arg_prefix" ||
 			die "fatal: '$arg_prefix' does not exist; use 'git subtree add'"
@@ -969,12 +966,6 @@ cmd_split () {
 	else
 		die "fatal: you must provide exactly one revision, and optionally a repository.  Got: '$*'"
 	fi
-
-	# Now validate prefix against the commit, not the working tree
-	if ! git ls-tree -d "$rev" -- "$dir" >/dev/null
-	then
-		die "fatal: '$dir' does not exist in commit $rev"
-	fi
 	repository=""
 	if test "$#" = 2
 	then

contrib/subtree/t/t7900-subtree.sh

@@ -368,28 +368,6 @@ test_expect_success 'split requires path given by option --prefix must exist' '
 	)
 '
 
-test_expect_success 'split works when prefix exists in commit but not in working tree' '
-	subtree_test_create_repo "$test_count" &&
-	(
-		cd "$test_count" &&
-
-		# create subtree
-		mkdir pkg &&
-		echo ok >pkg/file &&
-		git add pkg &&
-		git commit -m "add pkg" &&
-		good=$(git rev-parse HEAD) &&
-
-		# remove it from working tree in later commit
-		git rm -r pkg &&
-		git commit -m "remove pkg" &&
-
-		# must still be able to split using the old commit
-		git subtree split --prefix=pkg "$good" >out &&
-		test -s out
-	)
-'
-
 test_expect_success 'split rejects flags for add' '
 	subtree_test_create_repo "$test_count" &&
 	subtree_test_create_repo "$test_count/sub proj" &&