Long standing exhausting thread pool SSHD bug was apparently fixed
upstream [1].
All Gerrit releases since 2.8.5 are known to suffer from this problem
with the consequence that Gerrit must be restarted overnight.
[1] https://issues.apache.org/jira/browse/SSHD-348
Change-Id: Ic52277050aa0cd19b19531ee997d312fd7273ebc