Revert "bot_update: speculative fix for gerrit patch application failure."

This reverts commit 2b4da1228f.

Reason for revert: likely broke Angle http://crbug.com/692140

Original change's description:
> bot_update: speculative fix for gerrit patch application failure.
> 
> bot_update doesn't properly cleanup git index state from unmerged paths,
> which are likely if Rietveld patches were failed to be applied in prior
> runs in the same checkout dir.
> 
> R=​machenbach@chromium.org
> BUG=692067
> 
> Change-Id: I8fd326caefce8623731697a368cbad3159405257
> Reviewed-on: https://chromium-review.googlesource.com/442426
> Commit-Queue: Andrii Shyshkalov <tandrii@chromium.org>
> Reviewed-by: Michael Achenbach <machenbach@chromium.org>
> 

TBR=machenbach@chromium.org,tandrii@chromium.org,chromium-reviews@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=692067,692140

Change-Id: Iec808f28f3a0af99914a279536bb20a8975e02ba
Reviewed-on: https://chromium-review.googlesource.com/442485
Commit-Queue: Andrii Shyshkalov <tandrii@chromium.org>
Reviewed-by: Andrii Shyshkalov <tandrii@chromium.org>

recipe_modules/bot_update/resources/bot_update.py

@@ -659,12 +659,6 @@ def apply_gerrit_ref(gerrit_repo, gerrit_ref, root, gerrit_reset,
   print '===Applying gerrit ref==='
   print 'Repo is %r @ %r, ref is %r, root is %r' % (
       gerrit_repo, base_rev, gerrit_ref, root)
-  # TODO(tandrii): move the fix below to common rietveld/gerrit codepath.
-  # Speculative fix: prior bot_update run with Rietveld patch may leave git
-  # index with unmerged paths. bot_update calls 'checkout --force xyz' thus
-  # ignoring such paths, but potentially never cleaning them up. The following
-  # command will do so. See http://crbug.com/692067.
-  git('reset', '--hard', cwd=root)
   try:
     git('retry', 'fetch', gerrit_repo, gerrit_ref, cwd=root, tries=1)
     git('checkout', 'FETCH_HEAD', cwd=root)