patch 8.0.0442: patch shell command not well escaped

Problem:    Patch shell command uses double quotes around the argument, which
            allows for $HOME to be expanded. (Etienne)
Solution:   Use single quotes on Unix. (closes #1543)

src/diff.c

@@ -977,7 +977,12 @@ ex_diffpatch(exarg_T *eap)
     {
 	/* 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\"",
+	vim_snprintf((char *)buf, buflen,
+#ifdef UNIX
+		"patch -o %s %s < '%s'",
+#else
+		"patch -o %s %s < \"%s\"",
+#endif
 		tmp_new, tmp_orig,
 # ifdef UNIX
 		fullname != NULL ? fullname :

src/testdir/test_diffmode.vim

@@ -318,9 +318,20 @@ func Test_diffpatch()
   bwipe!
   new
   call assert_fails('diffpatch Xpatch', 'E816:')
+
+  for name in ['Xpatch', 'Xpatch$HOME']
     call setline(1, ['1', '2', '3'])
-  diffpatch Xpatch
+    if name != 'Xpatch'
+      call rename('Xpatch', name)
+    endif
+    exe 'diffpatch ' . escape(name, '$')
     call assert_equal(['1', '2x', '3', '4'], getline(1, '$'))
+    if name != 'Xpatch'
+      call rename(name, 'Xpatch')
+    endif
+    bwipe!
+  endfor
+
   call delete('Xpatch')
   bwipe!
 endfunc

src/version.c

@@ -764,6 +764,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    442,
 /**/
     441,
 /**/