patch 8.0.0333: illegal memory access when 'complete' ends in a backslash

Problem:    Illegal memory access when 'complete' ends in a backslash.
Solution:   Check for trailing backslash. (Dominique Pelle, closes #1478)

src/option.c

@@ -7017,7 +7017,7 @@ did_set_string_option(
 		    /* skip optional filename after 'k' and 's' */
 		    while (*s && *s != ',' && *s != ' ')
 		    {
-			if (*s == '\\')
+			if (*s == '\\' && s[1] != NUL)
 			    ++s;
 			++s;
 		    }

src/testdir/test_options.vim

@@ -136,6 +136,15 @@ func Test_thesaurus()
   call Check_dir_option('thesaurus')
 endfun
 
+func Test_complete()
+  " Trailing single backslash used to cause invalid memory access.
+  set complete=s\
+  new
+  call feedkeys("i\<C-N>\<Esc>", 'xt')
+  bwipe!
+  set complete&
+endfun
+
 func Test_set_completion()
   call feedkeys(":set di\<C-A>\<C-B>\"\<CR>", 'tx')
   call assert_equal('"set dictionary diff diffexpr diffopt digraph directory display', @:)

src/version.c

@@ -764,6 +764,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    333,
 /**/
     332,
 /**/