FLOGFILE= is not compatible with trial --until-failure. That form of repeat-until-failure works by starting and stopping the reactor over and over within a single process, which is pretty unusual: most of the time, the reactor starts shortly after the process begins, and runs until the process terminates. FLOGFILE= only opens the logfile once, but closes it each time the reactor shuts down, which isn't a good fit for unusual reactor cycling.
I generally use a small perl script to run a single test until it fails (using a new process for each iteration). I'll attach it here.
(also, I always use a FLOGFILE= that ends in just .flog instead of .flog.bz2, because the latter is more easily lost if the process terminates unexpectedly.)
