A user created this story earlier:
https://secure.phabricator.com/feed/5986919677825776582/
The task is:
https://secure.phabricator.com/T3848
The story looks like this:
mysql> select * from feed_storydata where chronologicalKey = '5986919677825776582'\G
*************************** 1. row ***************************
id: 80430
phid: PHID-STRY-bmglgbj3b4zpva2pr44q
chronologicalKey: 5986919677825776582
storyType: PhabricatorApplicationTransactionFeedStory
storyData: {"objectPHID":"PHID-TASK-codp5cwfcb76jv6rijqd","transactionPHIDs":["PHID-XACT-TASK-dx73bqvyyvuckhc"]}
authorPHID: PHID-USER-wp5a7h2gixwnx5ncmija
dateCreated: 1393938362
dateModified: 1393938362
1 row in set (0.00 sec)
The transaction looks like this:
mysql> select * from phabricator_maniphest.maniphest_transaction where phid = 'PHID-XACT-TASK-dx73bqvyyvuckhc'\G
*************************** 1. row ***************************
id: 51139
phid: PHID-XACT-TASK-dx73bqvyyvuckhc
authorPHID: PHID-USER-wp5a7h2gixwnx5ncmija
objectPHID: PHID-TASK-codp5cwfcb76jv6rijqd
viewPolicy: public
editPolicy: PHID-USER-wp5a7h2gixwnx5ncmija
commentPHID: NULL
commentVersion: 0
transactionType: subpriority
oldValue: "-174464453"
newValue: {"newPriority":"90","newSubpriorityBase":"-174484933"}
contentSource: {"source":"web","params":{"ip":"46.165.240.163"}}
metadata: []
dateCreated: 1393938362
dateModified: 1393938362
1 row in set (0.00 sec)
I'm guessing he dragged the task, changing its subpriority, and we're just missing some code somewhere to disable publishing feed stories for these new subpriority transactions. We hide the actual transactions on the task itself.