[gimp] app: add some warning for code which should not happen.

[Jehan Pagès <jehanp src gnome org>]

commit cdfffc692489d2e45e7366b3008ed22e5ec7736b
Author: Jehan <jehan girinstud io>
Date:   Tue Dec 26 17:47:05 2017 +0100

    app: add some warning for code which should not happen.

 app/core/gimp-user-install.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/app/core/gimp-user-install.c b/app/core/gimp-user-install.c
index 326fe3a..70268e5 100644
--- a/app/core/gimp-user-install.c
+++ b/app/core/gimp-user-install.c
@@ -570,6 +570,7 @@ user_update_menurc_over20 (const GMatchInfo *matched_value,
    */
   else
     {
+      g_message ("(WARNING) %s: invalid match \"%s\"", G_STRFUNC, match);
       g_string_append (new_value, match);
     }
 
@@ -636,6 +637,7 @@ user_update_gimpressionist (const GMatchInfo *matched_value,
     }
   else
     {
+      g_message ("(WARNING) %s: invalid match \"%s\"", G_STRFUNC, match);
       g_string_append (new_value, match);
     }