On Fri, 25 Mar 2016, Bernhard Übelacker wrote: [...]
one point that could be related is the usage of function local static variables. When all of these got the "static" removed, I do not get the failures anymore. However I could not prove this with testbot as an empty patch did also succeed.
The TestBot's build machine is still on Debian 7 (though it should be upgraded at some point). That would explain the difference.