[meld/ui-next] ui.statusbar: Add a comment on where the assertion comes from

[Kai Willadsen <kaiw src gnome org>]

commit 2cc500dd885133d1e025f2b2765a630de6709e33
Author: Kai Willadsen <kai willadsen gmail com>
Date:   Sun Mar 24 09:32:54 2019 +1000

    ui.statusbar: Add a comment on where the assertion comes from
    
    We can't fix this in Meld, and the fix isn't likely to come upstream any
    time soon... but we still want this handling.

 meld/ui/statusbar.py | 2 ++
 1 file changed, 2 insertions(+)
---
diff --git a/meld/ui/statusbar.py b/meld/ui/statusbar.py
index f1e065a9..825ee210 100644
--- a/meld/ui/statusbar.py
+++ b/meld/ui/statusbar.py
@@ -166,6 +166,8 @@ class MeldStatusBar(Gtk.Statusbar):
             line, offset = self.props.cursor_position
             entry.set_text(str(line + 1))
 
+        # This handler causes a failed assertion due to the `position`
+        # out param (see pygobject#12), but we don't need it here.
         def line_entry_insert_text(entry, new_text, length, position):
             if not new_text.isdigit():
                 GObject.signal_stop_emission_by_name(entry, 'insert-text')