We found that in Gerrit 2.1.6.1 (which is the latest release) reflog is disabled for all newly created projects.
Means: core.logallrefupdates=false
you may not be aware of that same as we were not :-)
This change in Gerrit behavior was introduced by the JGit change ffc8b42957a2f294960d5ad027e2c7e41d3f70cd
which sets core.logallrefupdates to !bare. Means for bare repositories to false.
This is correct according to CGit documentation:
http://www.kernel.org/pub/software/scm/git/docs/git-config.html
however, it is not what Gerrit admins expect from previous behavior.
We will try to provide Gerrit patch for this issue today where we would return to the old behavior
by explicitly setting core.logallrefupdates to true after Git repo is initialized.
Sasa Zivkov