UserAgent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/59.0.3071.115 Safari/537.36

Steps to reproduce the problem:
On an ARMv7 Linux host:

1. GN bootstrap fails from a standalone checkout

$ git clone https://chromium.googlesource.com/chromium/src/tools/gn/
$ cd gn
$ ./bootstrap/bootstrap.py 
...
OSError: [Errno 2] No such file or directory
...
It seems to want a full Chromium tree.

2. gclient fails to produce a Chromium tree.

$ fetch chromium
Bootstrapping cipd client for linux-armv7l...
From https://chrome-infra-packages.appspot.com/client?platform=linux-armv7l&version=git_revision:5cf65fdf804a9b3f3023f79d5b3cab2a88ccd09e
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0
curl: (22) The requested URL returned error: 404 

What is the expected behavior?
Output of a working GN executable.

What went wrong?
.

Did this work before? N/A 

Chrome version: 59.0.3071.115  Channel: n/a
OS Version: 
Flash Version: 

It used to be possible to use Chromium build tools on any Linux system. In particular, downstream projects like Dart that are effectively forced to use the Chromium build tools had working builds on ARM/ARM64/MIPS systems, but have regressed due to the switch from GYP to GN.