Ah, looks like the part of bug 1242904 that was backported is just the security fix, not the entire library version update and the version update is in 46. So

Ah, looks like the part of bug 1242904 that was backported is just the security fix, not the entire library version update and the version update is in 46. So what you could be seeing is something like https://bugzilla.mozilla.org/show_bug.cgi?id=1254411 https://bugzilla.mozilla.org/show_bug.cgi?id=1254411 Of course the version update wasn't supposed to change the on-the-wire behavior... or so the library authors claimed. :(