Unexpected grade for assessment calculated by workshop

This was observed by tsala while she was evaluating the MOOC workshop today at learn.moodle.net site. The following description is slightly simplified from the real situation but it illustrates the situation well (and could be used as steps to reproduce).

STEPS TO REPRODUCE

• There is a workshop, using the grading strategy "Number of errors".
• The assessment form has three assertions (dimensions), all with the same weight 1.
• There was a submission made by a participant Alice that was peer-reviewed by three other participants Bob, Cindy and Dan.
• Bob assessed the submission and filled the assessment form with No, No, No.
• Both Cindy and Dan assessed the submission and filled the assessment form with Yes, Yes, Yes.
• Helen (as the workshop facilitator/teacher) used the grading evaluation method "Comparison with the best assessment" during the grading evaluation phase to calculate the final grades.
• Helen realized that Bob's assessment is wrong and that Cindy and Dan are right. So she set the weight of Bob's assessment to 0 (zero) and re-calculated grades.

EXPECTED BEHAVIOUR

Bob should get very low grade for this assessment and both Cindy and Dan should get full grade for their assessments.

WHAT ACTUALLY HAPPENED

Bob got the full grade for his assessment, too.