User-Agent: Mozilla/5.0 (compatible; Konqueror/3.5) KHTML/3.5.10 (like Gecko) Build Identifier: When marking B as duplicate of A, check that A is actually older than B. If not, the user is probably about to make a mistake (confusing the 2 bug reports). Under some exceptional circumstances, it is maybe appropriate to mark an older bug as a duplicate of a newer. But then require a special field to be filled with an explanation of that circumstance. (Some more rationale, in case someone did not get it yet: Marking a bug as a duplicate is like telling the reporter that he should have searched better before reporting. But if the bug report that his report is marked a duplicate of did not yet exist, there was no way that he could have found it.) Reproducible: Always
That's not something we want to see implemented. There are different reasons why it makes sense to mark an older bug as a dupe of a newer one (better description, a long CC list, an already reviewed patch, etc...). A warning or something similar is in 99% of cases not desired.