patch 8.2.3405: cannot have a comment line in a {} block of a user command

Problem:    Cannot have a comment line in a {} block of a user command.
Solution:   Continue after the line break. (closes #8837)
diff --git a/src/ex_docmd.c b/src/ex_docmd.c
index 5898073..c58c414 100644
--- a/src/ex_docmd.c
+++ b/src/ex_docmd.c
@@ -2807,7 +2807,16 @@
 
 	// ignore comment and empty lines
 	if (comment_start(eap->cmd, starts_with_colon))
+	{
+	    // a comment ends at a NL
+	    if (eap->nextcmd == NULL)
+	    {
+		eap->nextcmd = vim_strchr(eap->cmd, '\n');
+		if (eap->nextcmd != NULL)
+		    ++eap->nextcmd;
+	    }
 	    return FAIL;
+	}
 	if (*eap->cmd == NUL)
 	{
 	    if (!skip_only)