patch 9.0.0456: function called at debug prompt is also debugged

Problem:    Function called at debug prompt is also debugged.
Solution:   Reset the debug level while entering the debug command.
            (closes #11118)
diff --git a/src/debugger.c b/src/debugger.c
index e2f73cc..235d493 100644
--- a/src/debugger.c
+++ b/src/debugger.c
@@ -135,9 +135,14 @@
 	    ignore_script = TRUE;
 	}
 
+	// don't debug any function call, e.g. from an expresion mapping
+	n = debug_break_level;
+	debug_break_level = -1;
+
 	vim_free(cmdline);
 	cmdline = getcmdline_prompt('>', NULL, 0, EXPAND_NOTHING, NULL);
 
+	debug_break_level = n;
 	if (typeahead_saved)
 	{
 	    restore_typeahead(&typeaheadbuf, TRUE);
diff --git a/src/version.c b/src/version.c
index 3b143a4..85e5a9d 100644
--- a/src/version.c
+++ b/src/version.c
@@ -704,6 +704,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    456,
+/**/
     455,
 /**/
     454,