update prepare script

scripts/prepare_singularity.py

@@ -6,6 +6,11 @@ import json
 
 def get_job_ad():
     instream = sys.stdin
+    # dump the input stream to a file for debugging
+    with open("/scratch/job_ad.txt", "w") as f:
+        for line in instream:
+            f.write(line)
+
     job_ad = {}
     # format of the job ad is key = value
     for line in instream: