Don't have checkout.py's git apply_patch fail when files don't match

Don't have checkout.py's git apply_patch fail when files don't match

The contract for apply_patch is that it applies a patch on top of something, and
it either all applies cleanly or it fails.  The something that is applied on can
be as clean or dirty without having apply_patch judge.  The particular failure
condition was that we want to patch DEPS first (into the index), do some stuff,
then apply another patch on top of that.  Apply_patch was failing because it
saw that there was a DEPS in the index already when it wasn't expecting one.

A fix that could've also worked is to run git diff --staged before applying the
patch, then subtract that list from found_files, but it still gets tricky then
because what if you want to apply an independent patch on top of
an already patched index?  

Because apply_patch shouldn't need to be in the business of
keeping track of what the state of everything is like before and
after a patch (That's up to the patch application), the better thing would be to remove the assert
alltogether, and rely on "git apply" to complain if something doesn't apply.

BUG=370503
TBR=iannucci

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=269526

[hinoka, 2014-05-10 04:35:41]

Tested with:
apply_issue --issue 273953002 --patchset 170001 --blacklist
device/bluetooth/bluetooth_adapter_chromeos.cc
apply_issue --issue 273953002 --patchset 170001 --whitelist
device/bluetooth/bluetooth_adapter_chromeos.cc

apply_issue found the extra files, but returned 0 on the second pass.

[hinoka, 2014-05-10 04:39:11]

The CQ bit was checked by hinoka@chromium.org

[commit-bot: I haz the power, 2014-05-10 04:40:01]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/hinoka@chromium.org/280023004/1

[commit-bot: I haz the power, 2014-05-10 04:42:49]

Change committed as 269526

[iannucci, 2014-05-10 21:47:52]

lgtm

[M-A Ruel, 2014-05-12 12:35:54]

https://codereview.chromium.org/280023004/diff/1/checkout.py
File checkout.py (right):

https://codereview.chromium.org/280023004/diff/1/checkout.py#newcode714
checkout.py:714: print 'Found extra files: %r' % (extra_files,)
I disagree that checkout.py should ever "print" at all. It's the wrong layer.

It could have easily been fixed by noting what was staged first, before applying
patches, then using this information to not consider them. Or remove the assert
completely, it was more as an internal debugging tool.

https://codereview.chromium.org/280023004/diff/1/checkout.py#newcode718
checkout.py:718: 
One superfluous line.