Comment 7 for bug 1255419

The upshot of that summit session was that there was a fair amount of support for the idea of capping dependencies we don't produce in the requirements files on stable branches of projects participating in our integrated release, but that we should seek further consensus prior to doing so. This bug, on the other hand, is about a dependency we *do* produce but which does not itself participate in the integrated release, and the intent there was that we should introduce additional backward compatibility testing in the gate to insure against client projects introducing changes (including transitive dependencies) which are incompatible with stable release branches of projects interacting with or consuming them. Basically once a client project merged a change to require a newer iso8601 than was allowed in one or more stable server branches, integration gating was instantly broken for that stable release.

It was suggested in bug 1242501 as well as other places (notably during discussions with Mark W. and other Glance devs on #openstack-infra shortly prior to the summit) that they should pursue support for both iso8601 0.1.4 and 0.1.8, but this was rejected at the time because it meant either exhibiting inconsistent behavior depending on which was installed or reimplementing a significant amount of iso8601 0.1.8 in Glance. If the proposed backward-compat testing were in place, the only options to get newer is08601 support through the gate would have been for Glance to support both, or for the stable branches of projects to be fixed such that they would also work with newer iso8601.