Reopening. A similar hang is occasionally occurring again with Jenkins 1.6.13 - 1.6.15 and Workflow 1.6 during bat steps in Windows. The process that workflow is waiting for has successfully ended according to log output, there are no rogue generated batch files and directories left either, so it still seems like a race condition exists.
Why is this concatenating to a jenkins-results.txt file anyway, that doesn't seem very robust? Can't we just re-pipe standard out and standard error directly?