Remove code in gsutil that removes http_proxy from the env var

boto config does the right thing by using the http_proxy env var to set the proxy,
and gsutil removes that var which isn't the behavior we want.
This should allow gsutil to respect the http_proxy env var.

BUG=318478

Review URL: https://codereview.chromium.org/68763013

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@235818 0039d316-1c4b-4281-b951-d872f2087c98

third_party/gsutil/CHECKSUM

-010822c61d38d70ac23600bc955fccf5
+c9cffb512f467c0aa54880788b9ee6ca

third_party/gsutil/README.chromium

@@ -14,6 +14,7 @@ Modifications:
 * Moved gsutil/boto as a depot_tools third_party lib
 * Moved gsutil/third_party into our own third_party directory
 * Append sys.path in gsutil/gsutil to find the moved third_party modules
-* Updated checksum ce71ac982f1148315e7fa65cff2f83e8 -> bf29190007bc7557c33806367ee3ce9e 
+* Updated checksum ce71ac982f1148315e7fa65cff2f83e8 -> c9cffb512f467c0aa54880788b9ee6ca
+* Remove code to remove http_proxy before boto.config invocation.
 
 Full license is in the COPYING file.

third_party/gsutil/gsutil

@@ -186,14 +186,6 @@ def main():
   else:
     command_name = args[0]
 
-  # Unset http_proxy environment variable if it's set, because it confuses
-  # boto. (Proxies should instead be configured via the boto config file.)
-  if 'http_proxy' in os.environ:
-    if debug > 1:
-      sys.stderr.write(
-          'Unsetting http_proxy environment variable within gsutil run.\n')
-    del os.environ['http_proxy']
-
   return _RunNamedCommandAndHandleExceptions(command_runner, command_name,
                                              args[1:], headers, debug,
                                              parallel_operations)