Looks like ssh works today. I'm investigating.

Lots of _gclient_src_* files in the builder directory:

chrome-bot@VM192-M3 /cygdrive/e/b/build/slave/dartium-win-debug-dev/build
$ du -kscx *
4443739 _gclient_src_106da_
3841495 _gclient_src_15gpr5
3696647 _gclient_src_3cvbqt
1071831 _gclient_src_3kmuyk
3836319 _gclient_src_3plxom
4018379 _gclient_src_6lmwy8
4405355 _gclient_src_7xfyrq
3730499 _gclient_src_81esqg
4420851 _gclient_src_bbsb4q
4065155 _gclient_src_bgfbde
4423435 _gclient_src_bnyvn8
4534383 _gclient_src_c8v_ww
...
4527171 _gclient_src_vnsqkf
3809507 _gclient_src_vqbdkd
4086751 _gclient_src_wqvth4
1451867 _gclient_src_wuv67f
3880391 _gclient_src_y0pp2r
3980223 _gclient_src_yb2yrh
4268335 _gclient_src_yqjgoq
3832403 _gclient_src_zg6onv
3880495 _gclient_src_zq4d1l
212929  src
243157789       total

I will clean up those directories and make sure they're deleted automatically as well.

The root cause seems to be a builder misconfiguration though. We're getting those messages in the build logs: 

gclient.bat recurse -i sh -c "if [ -e .git ]; then git remote update; fi"
'sh' is not recognized as an internal or external command,

https://build.chromium.org/p/client.dart.fyi/builders/dartium-win-debug-dev/builds/240/steps/gclient_revert/logs/stdio

+whesse FYI.

Disk usage is down to 82%. I haven't deleted all those stray directories yet, to be able to check the automatic cleanup works when I get to it.

The following revision refers to this bug:
  https://chrome-internal.googlesource.com/infra/infra_internal.git/+/60d398722a060a7a40b52b0ff5ffbbedf60b65bf

commit 60d398722a060a7a40b52b0ff5ffbbedf60b65bf
Author: pgervais <pgervais@google.com>
Date: Fri Jun 24 00:39:44 2016

The following revision refers to this bug:
  https://chrome-internal.googlesource.com/infra/puppet/+/7a052b3105a8e03eef2100852f6a81e694883c87

commit 7a052b3105a8e03eef2100852f6a81e694883c87
Author: Philippe Gervais <pgervais@google.com>
Date: Fri Jun 24 01:00:59 2016

The following revision refers to this bug:
  https://chrome-internal.googlesource.com/infra/puppet/+/1c5418b9dca20f806461fdab6835ef74249ce92f

commit 1c5418b9dca20f806461fdab6835ef74249ce92f
Author: Philippe Gervais <pgervais@google.com>
Date: Mon Jun 27 17:17:45 2016

Seems like a stale issue. The disks are at C: 54%, E: 15% utilization.