https://uberchromegw.corp.google.com/i/chromeos/builders/nyan-release

9 of the last 10 builds failed signing.

The log shows:
** Start Stage Signing - Tue, 24 May 2016 21:01:28 -0700 (PDT)
...
21:01:28: INFO: Waiting for image signing for: nyan, 8369.0.0
21:01:28: INFO: GS errors are a normal part of the polling for results.
21:01:28: INFO: Waiting for signer results.
...
21:51:22: INFO: RunCommand: /b/cbuild/internal_master/.cache/common/gsutil_4.19.tar.gz/gsutil/gsutil -o 'Boto:num_retries=10' cat gs://chromeos-releases/canary-channel/nyan/8369.0.0/ChromeOS-recovery-R53-8369.0.0-nyan.instructions.json
21:52:22: WARNING: GS_ERROR: Traceback (most recent call last):
...
socket.timeout: timed out

So, signing stage times out after ~50 minutes.

I can manually run the command:
gsutil -o 'Boto:num_retries=10' cat gs://chromeos-releases/canary-channel/nyan/8369.0.0/ChromeOS-recovery-R53-8369.0.0-nyan.instructions.json

Here is the result:

{"status": {"status": "passed", "summary": "", "details": "", "current-time": "Wed, 25 May 2016 04:53:25 +0000 (UTC)"}, 
 "keyset_is_mp": false, "metadata-version": "1", "input-archive": "ChromeOS-recovery-R53-8369.0.0-nyan.tar.xz",
 "bot-hostname": "chromeos-signing16.hot.corp.google.com", "keyset": "nyan-premp",
 "version": {"platform": "8369.0.0", "full": "R53-8369.0.0", "milestone": "53"}, 
 "board": "nyan", "time": {"finish": "Wed, 25 May 2016 04:53:12 +0000 (UTC)", 
 "upload": { "chromeos_8369.0.0_nyan_recovery_canary-channel_premp.bin": {"duration": "0:02:16.015533", "start": "Wed, 25 May 2016 04:50:54 +0000 (UTC)"} },
 "sign": {"recovery_image.bin": {"duration": "0:04:17.036300", "start": "Wed, 25 May 2016 04:46:21 +0000 (UTC)"}}, 
 "start": "Wed, 25 May 2016 04:45:11 +0000 (UTC)", 
 "download": {"duration": "0:00:10.790948", "start": "Wed, 25 May 2016 04:45:16 +0000 (UTC)"}, 
 "unpack": {"duration": "0:00:46.564516", "start": "Wed, 25 May 2016 04:45:31 +0000 (UTC)"}}, 
 "type": "recovery", "channel": "canary"
}

So, signing did eventually succeed, but it took a while, finishing at:
 Wed, 25 May 2016 04:53:25 +0000 (UTC)

Which (converting time-zones to PDT is: 21:53:25

Or, about 1 minute after the bot gave up.

So, is there a 'signer time out' that needs to be extended?