newly created directories not always available fro remote job

[flowers9]

This is similar to an earlier issue I commented on, and still appears to be an issue. The wrapper script created by simple_pwatcher_bridge.py tries to cd {wdir}, and it fails because that directory hasn't yet propogated from the program's head node to the remote node the job is run on. This one has a very simple fix:

--- simple_pwatcher_bridge.py 2017-05-31 10:57:47.317485000 -0500
+++ simple_pwatcher_bridge.py 2017-05-31 10:58:59.469657000 -0500
@@ -350,6 +350,7 @@
rel_actual_script_fn = os.path.relpath(actual_script_fn, wdir)
wrapper = """#!/bin/sh
set -vex
+mkdir -p {wdir}
cd {wdir}
bash {rel_actual_script_fn}
touch {sentinel_done_fn}

mkdir -p will return success if the directory already exists, and the attempt to create the directory forces it to propogate to the node the job is running on.

[pb-cdunn]

The wrappers (which run from the installation, not from the remote directory) should now cause the remote job to wait for all known input files to become available.