Unfortunately this codepath wasn't well tested. :/ We found this when ShrutiJ was working on bug 1289138. It was first introduced in bug 1278800, I'm a bit embarassed that I didn't notice the problem when reviewing the patch there.
Comment on attachment 8776062 [details] [review] [treeherder] wlach:1290525 > mozilla:master Hey Ed, can you take a look at this one? It's pretty simple -- perhaps ideally we would do some refactoring to make this mistake harder to make, but I figured it might not be worth it to go that far since we're moving away from buildbot (I also didn't want to block ShrutiJ's work on a more involved solution)
Commit pushed to master at https://github.com/mozilla/treeherder https://github.com/mozilla/treeherder/commit/420bd613062432857a460d193a93a4313e3c17ad Bug 1290525 - Fix cancelling buildbot jobs from revision bar (#1752)