When trying to regrade quiz attemtp, User's Outline Report shows the regrade date rather than teh last quiz attempt date.

To reproduce:
1. create a quiz in a coirse and allow student to attempt it
2. now close the quiz (not sure ithis step is significant)
3. access a user's Outline Report. The date shown is correctly the last access to the Quiz
4. access Quiz result and regrade quizzes
5. access again the user's Outline Report. The date shown for the Quiz is now the date of the regrade
6. access the very same user's Complete report. Date shown here are correct, so there is a discrepancy among the two report.

Possible solutions (thanks to Eloy):
1) Make the "regrade" not to modify dates.
2) Make the report to use the attempt grade (like the complete report does)

My +1 for the second option.