Run `svn cleanup` before every update and reset.

Run `svn cleanup` before every update and reset.

Testing on a bot with an 'unclean' Chromium checkout:

Unpatched `gclient revert -v -v -v --nohooks --upstream` (unclean checkout)
real    9m14.280s
user    0m37.238s
sys     0m37.738s

Patched 'gclient revert -v -v -v --nohooks --upstream'  (unclean checkout)
real    5m50.065s
user    1m18.889s
sys     0m57.860s

---------------- after patched gclient revert run (cleans the checkout)

Unpatched 'gclient revert -v -v -v --nohooks --upstream' (clean checkout)
real    0m21.602s
user    0m24.966s
sys     0m13.969s

Patched 'gclient revert -v -v -v --nohooks --upstream' (clean checkout)
real    0m27.467s
user    0m28.382s
sys     0m22.629s

BUG=336983
Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=264753

[ghost stip (do not use), 2014-04-17 08:59:35]

This should be the end of crbug.com/336983.

[Dirk Pranke, 2014-04-17 18:21:40]

lgtm

[iannucci, 2014-04-17 18:25:32]

On 2014/04/17 18:21:40, Dirk Pranke wrote:
> lgtm

Mike, can you verify performance figures for this on windows first?

[ghost stip (do not use), 2014-04-17 21:35:40]

On 2014/04/17 18:25:32, iannucci wrote:
> On 2014/04/17 18:21:40, Dirk Pranke wrote:
> > lgtm
> 
> Mike, can you verify performance figures for this on windows first?

Yes I can

[ghost stip (do not use), 2014-04-17 23:22:35]

Windows data:

Unpatched `gclient.bat revert -v -v -v --nohooks --upstream` with dirty
checkout:
2m29s

Patched unclean:
3m48s

Unpatched clean:
3m08s

Patched clean:
2m51s

So, at least on this bot there doesn't seem to be a performance difference (the
variance between runs is quite high). It's also possible that this checkout was
clean and just takes a while.

[ghost stip (do not use), 2014-04-18 08:03:21]

The CQ bit was checked by stip@chromium.org

[commit-bot: I haz the power, 2014-04-18 08:03:30]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/stip@chromium.org/240503007/20001

[commit-bot: I haz the power, 2014-04-18 08:05:02]

Change committed as 264753

[ghost stip (do not use), 2014-04-21 22:16:17]

A revert of this CL has been created in
https://chromiumcodereview.appspot.com/245293003/ by stip@chromium.org.

The reason for reverting is: It's inconclusive if this actually helped the bots,
so reverting..