Is there a way in Subversion 1.6, using logs, mergeinfo, etc., to determine when a merge was done with the --reintegrate option? (This presumes one knows which commits are the results of merges.)
The only information stored is the list of revisions that were merged. How they were merged is not recorded.
You can make a good guess by examining the file contents, though: After a reintegrate merge, the only difference between merge source and merge destination will be those revisions of the merge destination that were not previously merged to the merge source.