patch 8.1.0640: get E14 while typing command :tab with 'incsearch' set

Problem:    Get E14 while typing command :tab with 'incsearch' set.
Solution:   Do not give an error when looking for the command. (Yasuhiro
            Higashi)

src/ex_docmd.c

@@ -2827,8 +2827,11 @@ parse_command_modifiers(exarg_T *eap, char_u **errormsg, int skip_only)
 
 	    case 't':	if (checkforcmd(&p, "tab", 3))
 			{
-			    long tabnr = get_address(eap, &eap->cmd, ADDR_TABS,
-					       eap->skip, skip_only, FALSE, 1);
+			    if (!skip_only)
+			    {
+				long tabnr = get_address(eap, &eap->cmd,
+						    ADDR_TABS, eap->skip,
+						    skip_only, FALSE, 1);
 				if (tabnr == MAXLNUM)
 				    cmdmod.tab = tabpage_index(curtab) + 1;
 				else
@@ -2840,6 +2843,7 @@ parse_command_modifiers(exarg_T *eap, char_u **errormsg, int skip_only)
 				    }
 				    cmdmod.tab = tabnr + 1;
 				}
+			    }
 			    eap->cmd = p;
 			    continue;
 			}

src/testdir/test_search.vim

@@ -783,6 +783,20 @@ func Test_search_cmdline_incsearch_highlight_attr()
   bwipe!
 endfunc
 
+func Test_incsearch_cmdline_modifier()
+  if !exists('+incsearch')
+    return
+  endif
+  call test_override("char_avail", 1)
+  new
+  call setline(1, ['foo'])
+  set incsearch
+  " Test that error E14 does not occur in parsing command modifier.
+  call feedkeys("V:tab", 'tx')
+
+  call Incsearch_cleanup()
+endfunc
+
 func Test_incsearch_scrolling()
   if !CanRunVimInTerminal()
     return

src/version.c

@@ -799,6 +799,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    640,
 /**/
     639,
 /**/