Create the output_dir for the test subcommand.

This change creates the output directory for the test subcommand if it
does not yet exist. If it exists, use it. Any other exceptions are
re-raised.

Change-Id: I487c69e70f9b6c475691ca4fef4669a0c318ab55

jenkins_jobs/builder.py

@@ -580,6 +580,11 @@ class Builder(object):
                 if names:
                     print job.output()
                     continue
+                try:
+                    os.makedirs(output_dir)
+                except OSError:
+                    if not os.path.isdir(output_dir):
+                        raise
                 fn = os.path.join(output_dir, job.name)
                 logger.debug("Writing XML to '{0}'".format(fn))
                 f = open(fn, 'w')