If check fails, recompute the workspace.
In principle would provide better recovery after 10s hangs like the following in buildShellScriptAcrossDisconnect.
In fact they still occur, and for reasons TBD the whole test times out (180s).
"CPS VM execution thread: …" Id=216 Group=main TIMED_WAITING on [B@1daef240
	at java.lang.Object.wait(Native Method)
	-  waiting on [B@1daef240
	at hudson.remoting.FastPipedInputStream.read(FastPipedInputStream.java:175)
	at hudson.remoting.FastPipedInputStream.read(FastPipedInputStream.java:151)
	at hudson.Util.copyStream(Util.java:460)
	at org.jenkinsci.plugins.durabletask.FileMonitoringTask$FileMonitoringController.writeLog(FileMonitoringTask.java:93)
	at org.jenkinsci.plugins.workflow.steps.durable_task.DurableTaskStep$Execution.check(DurableTaskStep.java:146)