Last modified: 2014-02-19 22:29:34 UTC
Eg. http://ee-flow.wmflabs.org/w/index.php?title=Sandbox&topic[newRevision]=050c9aba2dbff00fc8b1fa163e68c4ac&topic[oldRevision]=050b62277c1bf00fc8b1fa163e68c4ac&workflow=050afac360ebf00fc8b1fa163e68c4ac&action=compare-revisions In that edit: The anon must have clicked-to-edit the topictitle, and hit save, without making any actual changes (or after undoing any changes they typed). This "no-change action" currently would not get saved in the database, with regular wikipages (see [[WP:Null edit]]). It probably shouldn't in Flow, either.
The WMF core features team tracks this bug on Mingle card https://mingle.corp.wikimedia.org/projects/flow/cards/658, but people from the community are welcome to contribute here and in Gerrit.