Catch closed RP, fixes #334.

dataset/util.py

@@ -2,6 +2,7 @@ from hashlib import sha1
 from urllib.parse import urlparse
 from collections import OrderedDict
 from collections.abc import Iterable
+from sqlalchemy.exc import ResourceClosedError
 
 QUERY_STEP = 1000
 row_type = OrderedDict
@@ -19,6 +20,7 @@ def convert_row(row_type, row):
 
 def iter_result_proxy(rp, step=None):
     """Iterate over the ResultProxy."""
+    try:
         while True:
             if step is None:
                 chunk = rp.fetchall()
@@ -28,6 +30,8 @@ def iter_result_proxy(rp, step=None):
                 break
             for row in chunk:
                 yield row
+    except ResourceClosedError:
+        return
 
 
 class ResultIter(object):