[gtk/fix-double-underscore-mnemonic] label: Ignore __ for mnemonics

[Matthias Clasen <matthiasc src gnome org>]

commit c51f2fc0ecd967bffe8fe754de7e7bcc231f08fa
Author: Matthias Clasen <mclasen redhat com>
Date:   Sun Aug 1 22:14:12 2021 -0400

    label: Ignore __ for mnemonics
    
    We were not ignoring double underscores for mnemonics
    in one place, as we should.
    
    Fixes: #4129

 gtk/gtklabel.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/gtk/gtklabel.c b/gtk/gtklabel.c
index ced834f980..d4e414d882 100644
--- a/gtk/gtklabel.c
+++ b/gtk/gtklabel.c
@@ -3187,7 +3187,7 @@ strip_ulines (const char *text,
         }
 
       *q = *p;
-      if (after_uline && *accel_key == 0)
+      if (after_uline && *p != '_' && *accel_key == 0)
         *accel_key = g_utf8_get_char (p);
 
       q++;