burst_buffer/cray: work-around for cray API bug

The "paths" API is returning an error in some cases when it should
not, this adds logic to test the response string and process the
paths file produced when it actually does work.

src/plugins/burst_buffer/cray/burst_buffer_cray.c

@@ -2731,6 +2731,7 @@ extern int bb_p_job_validate2(struct job_record *job_ptr, char **err_msg)
 	    (resp_msg && !strncmp(resp_msg, "job_file_valid True", 19))) {
 		error("%s: paths for job %u status:%u response:%s",
 		      __func__, job_ptr->job_id, status, resp_msg);
+		_update_job_env(job_ptr, path_file);
 	} else
 #endif
 	if (!WIFEXITED(status) || (WEXITSTATUS(status) != 0)) {