patch 8.2.0810: error when appending "tagfile" to 'wildoptions'

Problem:    Error when appending "tagfile" to 'wildoptions'.
Solution:   use flags P_ONECOMMA and P_NODUP. (Dmitri Vereshchagin,
            closes #6105)

src/optiondefs.h

@@ -2837,7 +2837,7 @@ static struct vimoption options[] =
     {"wildmode",    "wim",  P_STRING|P_VI_DEF|P_ONECOMMA|P_NODUP,
 			    (char_u *)&p_wim, PV_NONE,
 			    {(char_u *)"full", (char_u *)0L} SCTX_INIT},
-    {"wildoptions", "wop",  P_STRING|P_VI_DEF,
+    {"wildoptions", "wop",  P_STRING|P_VI_DEF|P_ONECOMMA|P_NODUP,
 			    (char_u *)&p_wop, PV_NONE,
 			    {(char_u *)"", (char_u *)0L}
 			    SCTX_INIT},

src/testdir/test_options.vim

@@ -60,6 +60,13 @@ func Test_wildchar()
   set wildchar&
 endfunc
 
+func Test_wildoptions()
+  set wildoptions=
+  set wildoptions+=tagfile
+  set wildoptions+=tagfile
+  call assert_equal('tagfile', &wildoptions)
+endfunc
+
 func Test_options_command()
   let caught = 'ok'
   try

src/version.c

@@ -746,6 +746,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    810,
 /**/
     809,
 /**/