Fix running 'import run_isolated' at python interactive prompt.

utils/net.py

 # Copyright 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Classes and functions for generic network communication over HTTP."""
 
 import cookielib
 import cStringIO as StringIO
 import httplib
 import itertools
@@ skipping 301 matching lines @@
     raise TimeoutError exception whenever there's no response from the server
     for more than |read_timeout| seconds. It can happen during any read
     operation so once you pass non-None |read_timeout| be prepared to handle
     these exceptions in subsequent reads from the stream.
 
     Returns a file-like object, where the response may be read from, or None
     if it was unable to connect. If |stream| is False will read whole response
     into memory buffer before returning file-like object that reads from this
     memory buffer.
     """
-    assert urlpath and urlpath[0] == '/'
+    assert urlpath and urlpath[0] == '/', urlpath
 
     if data is not None:
       assert method in (None, 'POST', 'PUT')
       method = method or 'POST'
       content_type = content_type or DEFAULT_CONTENT_TYPE
       body = self.encode_request_body(data, content_type)
     else:
       assert method in (None, 'GET')
       method = method or 'GET'
       body = None
@@ skipping 432 matching lines @@
     attemp_obj = RetryAttempt(attempt, remaining)
     yield attemp_obj
     if attemp_obj.skip_sleep:
       continue
     # Only sleep if we are going to try again.
     if max_attempts and attempt != max_attempts - 1:
       remaining = (timeout - (current_time() - start)) if timeout else None
       if remaining is not None and remaining < 0:
         break
       sleep_before_retry(attempt, remaining)