(PDB-762) Fix broken export

This pull request fixes a malformed post-assertion in the events-for-report-hash
function that caused exports to fail on unchanged reports. Inserting proper
parentheses made it apparent that a seq, rather than a vector, should be the
expected return type.
Merge pull request #1015 from wkalt/ticket/stable/pdb-762-broken-export

(PDB-762) Fix broken export