Ignore IOErrors while we're still waiting

integration/util.py

@@ -7,8 +7,12 @@ def await_file_contents(path, contents, timeout=10):
     while time.time() - start_time < timeout:
         print("  waiting for '{}'".format(path))
         if exists(path):
+            try:
                 with open(path, 'r') as f:
                     current = f.read()
+            except IOError:
+                print("IOError; trying again")
+            else:
                 if current == contents:
                     return True
                 print("  file contents still mismatched")