patch 9.0.1440: "rvim" can execute a shell through :diffpatch

Problem:    "rvim" can execute a shell through :diffpatch.
Solution:   Disallow the shell "patch" command.
diff --git a/src/diff.c b/src/diff.c
index a46f0bf..1873767 100644
--- a/src/diff.c
+++ b/src/diff.c
@@ -1310,6 +1310,9 @@
     else
 #endif
     {
+	if (check_restricted())
+	    goto theend;
+
 	// Build the patch command and execute it.  Ignore errors.  Switch to
 	// cooked mode to allow the user to respond to prompts.
 	vim_snprintf((char *)buf, buflen, "patch -o %s %s < %s",
@@ -1380,7 +1383,8 @@
 
 		    // Do filetype detection with the new name.
 		    if (au_has_group((char_u *)"filetypedetect"))
-			do_cmdline_cmd((char_u *)":doau filetypedetect BufRead");
+			do_cmdline_cmd(
+				     (char_u *)":doau filetypedetect BufRead");
 		}
 	    }
 	}
diff --git a/src/testdir/test_diffmode.vim b/src/testdir/test_diffmode.vim
index d60de50..cb042e1 100644
--- a/src/testdir/test_diffmode.vim
+++ b/src/testdir/test_diffmode.vim
Binary files differ
diff --git a/src/version.c b/src/version.c
index 5cace2e3..853ea5f 100644
--- a/src/version.c
+++ b/src/version.c
@@ -696,6 +696,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1440,
+/**/
     1439,
 /**/
     1438,