UserAgent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/53.0.2785.143 Safari/537.36

Steps to reproduce the problem:
1. On new linux machine try to setup buildbot with below procedure.

- install buildbot and have your own working code of master & slave
- git clone https://chromium.googlesource.com/chromium/tools/build
- git clone https://chromium.googlesource.com/chromium/tools/depot_tools.git
- export PATH=`pwd`/depot_tools:"$PATH"
- fetch infra
- buildbot upgrade-master master(master directory)
observe below issue.
 from infra_libs import InstrumentedHttp
exceptions.ImportError: No module named infra_libs
Errors loading configuration:
  error while parsing config file: No module named infra_libs (traceback in logfile)

2. To solve this problem:
- Change the infra reference @ https://chromium.googlesource.com/chromium/tools/depot_tools/+/master/fetch_configs/infra.py#25 to point to new project    "https://chromium.googlesource.com/infra/infra/packages/infra_libs.git"
- fetch --force infra
- cd infra
- sudo python setup.py install

What is the expected behavior?
"fetch infra" should install all dependent packages required.

What went wrong?
It seems dependent packages installation issue with https://chromium.googlesource.com/chromium/tools/build/+/master/DEPS 

Refer https://groups.google.com/a/chromium.org/forum/#!topic/infra-dev/Had_R-R88qY for discussion on this issue.

Did this work before? Yes 

Chrome version: 55.0.2882.0  Channel: n/a
OS Version: 3.2 (Ubuntu Linux 12.04)
Flash Version: 

if we follow only below steps to setup buildbot

- install buildbot and have your own working code of master & slave
- git clone https://chromium.googlesource.com/chromium/tools/build
reverting the change https://codereview.chromium.org/2254643002 resolve the issue.

- buildbot upgrade-master master(master directory) is successful.