update-index --again

After running 'git-update-index' for some paths, you may want to
do the update on the same set of paths again.

The new flag --again checks the paths whose index entries are
are different from the HEAD commit and updates them from the
working tree contents.

This was brought up by Carl Worth on #git.

Signed-off-by: Junio C Hamano <junkio@cox.net>

t/t2101-update-index-reupdate.sh

@@ -0,0 +1,73 @@
+#!/bin/sh
+#
+# Copyright (c) 2006 Junio C Hamano
+#
+
+test_description='git-update-index --again test.
+'
+
+. ./test-lib.sh
+
+test_expect_success 'update-index --add' \
+	'echo hello world >file1 &&
+	 echo goodbye people >file2 &&
+	 git-update-index --add file1 file2 &&
+	 git-ls-files -s >current &&
+	 cmp current - <<\EOF
+100644 3b18e512dba79e4c8300dd08aeb37f8e728b8dad 0	file1
+100644 9db8893856a8a02eaa73470054b7c1c5a7c82e47 0	file2
+EOF'
+
+test_expect_success 'update-index --again' \
+	'rm -f file1 &&
+	echo hello everybody >file2 &&
+	if git-update-index --again
+	then
+		echo should have refused to remove file1
+		exit 1
+	else
+		echo happy - failed as expected
+	fi &&
+	 git-ls-files -s >current &&
+	 cmp current - <<\EOF
+100644 3b18e512dba79e4c8300dd08aeb37f8e728b8dad 0	file1
+100644 9db8893856a8a02eaa73470054b7c1c5a7c82e47 0	file2
+EOF'
+
+test_expect_success 'update-index --remove --again' \
+	'git-update-index --remove --again &&
+	 git-ls-files -s >current &&
+	 cmp current - <<\EOF
+100644 0f1ae1422c2bf43f117d3dbd715c988a9ed2103f 0	file2
+EOF'
+
+test_expect_success 'first commit' 'git-commit -m initial'
+
+test_expect_success 'update-index again' \
+	'mkdir -p dir1 &&
+	echo hello world >dir1/file3 &&
+	echo goodbye people >file2 &&
+	git-update-index --add file2 dir1/file3 &&
+	echo hello everybody >file2
+	echo happy >dir1/file3 &&
+	git-update-index --again &&
+	git-ls-files -s >current &&
+	cmp current - <<\EOF
+100644 53ab446c3f4e42ce9bb728a0ccb283a101be4979 0	dir1/file3
+100644 0f1ae1422c2bf43f117d3dbd715c988a9ed2103f 0	file2
+EOF'
+
+test_expect_success 'update-index --update from subdir' \
+	'echo not so happy >file2 &&
+	cd dir1 &&
+	cat ../file2 >file3 &&
+	git-update-index --again &&
+	cd .. &&
+	git-ls-files -s >current &&
+	cmp current - <<\EOF
+100644 d7fb3f695f06c759dbf3ab00046e7cc2da22d10f 0	dir1/file3
+100644 0f1ae1422c2bf43f117d3dbd715c988a9ed2103f 0	file2
+EOF'
+
+test_done
+