Comment 19 for bug 1903531

@Lajos Katona: There seems to be a fundamental misunderstanding of the issue here.
The initial change caused incompatibility between neutron-server and neutron-agent.
This is independent of the combination in 15.1 or 15.3 are running on either side: they are simply incompatible.

Reverting the change will just create yet another version that will be incompatible...
15.1 vs. 15.3 vs. 15.3-reverted will each be incompatible to their previous / following version.

Certainly if someone did not yet update to 15.3,is still running 15.1, would apply the 15.3-reverted version immediately would have no issues as the introduced incompatibility would have been removed from the code again.

But the issue remains with mixed environments, which is very likely for bigger installations as they cannot simply update every neutron-sever + agent at the same time. If one already went through the update to 15.3 (with the potential to have dysfunctional security groups in the meantime) the new version containing the revered change would create the same scenario yet again - rendering security groups potentially broken until neutron-server + neutron-agents are all running the new version.

In short: I don't think this issue is handled very well actually.