merge(third_party/git): Merge squashed git subtree at v2.23.0

Merge commit '1b593e1ea4' as 'third_party/git'

third_party/git/t/t2100-update-cache-badpath.sh

@@ -0,0 +1,61 @@
+#!/bin/sh
+#
+# Copyright (c) 2005 Junio C Hamano
+#
+
+test_description='git update-index nonsense-path test.
+
+This test creates the following structure in the cache:
+
+    path0       - a file
+    path1       - a symlink
+    path2/file2 - a file in a directory
+    path3/file3 - a file in a directory
+
+and tries to git update-index --add the following:
+
+    path0/file0 - a file in a directory
+    path1/file1 - a file in a directory
+    path2       - a file
+    path3       - a symlink
+
+All of the attempts should fail.
+'
+
+. ./test-lib.sh
+
+mkdir path2 path3
+date >path0
+if test_have_prereq SYMLINKS
+then
+	ln -s xyzzy path1
+else
+	date > path1
+fi
+date >path2/file2
+date >path3/file3
+
+test_expect_success \
+    'git update-index --add to add various paths.' \
+    'git update-index --add -- path0 path1 path2/file2 path3/file3'
+
+rm -fr path?
+
+mkdir path0 path1
+date >path2
+if test_have_prereq SYMLINKS
+then
+	ln -s frotz path3
+else
+	date > path3
+fi
+date >path0/file0
+date >path1/file1
+
+for p in path0/file0 path1/file1 path2 path3
+do
+	test_expect_success \
+	    "git update-index to add conflicting path $p should fail." \
+	    "test_must_fail git update-index --add -- $p"
+done
+test_done