patch: add -N and a test for it (fails for now)

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

testsuite/patch.tests

@@ -4,7 +4,7 @@
 
 . ./testing.sh
 
-# testing "test name" "options" "expected result" "file input" "stdin"
+# testing "test name" "command(s)" "expected result" "file input" "stdin"
 
 testing "patch with old_file == new_file" \
 	'patch 2>&1; echo $?; cat input' \
@@ -126,6 +126,31 @@ abc
 +456
 " \
 
+# testing "test name" "command(s)" "expected result" "file input" "stdin"
+
+testing "patch -N ignores already applied hunk" \
+	'patch -N 2>&1; echo $?; cat input' \
+"\
+patching file input
+0
+abc
+def
+123
+" \
+"\
+abc
+def
+123
+" \
+"\
+--- input
++++ input
+@@ -1,2 +1,3 @@
+ abc
++def
+ 123
+" \
+
 rm input.orig 2>/dev/null
 
 exit $FAILCOUNT