Diffusion mirrors of Gerrit repos not showing commits made since August 17
This is probably a known issue, but Diffusion doesn't seem to be showing changes made to the code since some time on August 17 - for core MediaWiki or any of the extensions or skins. You can see this for core MediaWiki here:
https://phabricator.wikimedia.org/source/mediawiki/history/master/
Is this an issue with Jenkins, maybe? Or maybe just a sign that Diffusion is on its way out?
---
The issue is due to Gerrit 3.4.4 to 3.4.5 upgrade (T315408). When trying to ssh on port 22 on the gerrit2002.wikimedia.org host (which serves gerrit-replica.wikimedia.org), the ssh connection can not be established:
```counterexample
Caused by: org.apache.sshd.common.SshException: KeyExchange signature verification failed for key type=ssh-rsa
```
Fix got to rollback to 3.4.4.
It is apparently a bug in Apache Mina SSH (which is upgrade from 2.6.0 to 2.7.0 by that Gerrit version). The Apache Mina SSH versions for Gerrit are:
```
$ git grep "SSHD_VERS =" v3.4.4 v3.4.5 v3.5.2 v3.6.1
v3.4.4:tools/nongoogle.bzl: SSHD_VERS = "2.6.0"
v3.4.5:tools/nongoogle.bzl: SSHD_VERS = "2.7.0"
v3.5.2:tools/nongoogle.bzl: SSHD_VERS = "2.7.0"
v3.6.1:tools/nongoogle.bzl: SSHD_VERS = "2.8.0"
```
It is apparently solved by 2.8.0 and thus Gerrit 3.6.
It might be possible to workaround the issue by regenerating the ssh key pair used for replication (and used by the `gerrit2` user).