patch 9.1.0713: Newline causes E749 in Ex mode

Problem:  Newline causes E749 in Ex mode (after 9.1.0573).
Solution: Don't execute empty command followed by a newline.

closes: #15614

Signed-off-by: zeertzjq <[email protected]>
Signed-off-by: Christian Brabandt <[email protected]>

Author: zeertzjq

src/ex_docmd.c

@@ -2916,6 +2916,11 @@ parse_command_modifiers(
 	    }
 	    return FAIL;
 	}
+	if (eap->nextcmd == NULL && *eap->cmd == '\n')
+	{
+	    eap->nextcmd = eap->cmd + 1;
+	    return FAIL;
+	}
 	if (*eap->cmd == NUL)
 	{
 	    if (!skip_only)

src/testdir/test_ex_mode.vim

@@ -387,4 +387,20 @@ func Test_global_insert_newline()
   bwipe!
 endfunc
 
+" An empty command followed by a newline shouldn't cause E749 in Ex mode.
+func Test_ex_empty_command_newline()
+  let g:var = 0
+  call feedkeys("gQexecute \"\\nlet g:var = 1\"\r", 'xt')
+  call assert_equal(1, g:var)
+  call feedkeys("gQexecute \"  \\nlet g:var = 2\"\r", 'xt')
+  call assert_equal(2, g:var)
+  call feedkeys("gQexecute \"\\t \\nlet g:var = 3\"\r", 'xt')
+  call assert_equal(3, g:var)
+  call feedkeys("gQexecute \"\\\"?!\\nlet g:var = 4\"\r", 'xt')
+  call assert_equal(4, g:var)
+  call feedkeys("gQexecute \"  \\\"?!\\nlet g:var = 5\"\r", 'xt')
+  call assert_equal(5, g:var)
+  unlet g:var
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab

src/version.c

@@ -704,6 +704,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    713,
 /**/
     712,
 /**/