Have git cache bootstrap repo if repo is corrupt
Have git cache bootstrap repo if repo is corrupt

We're seeing fetches fail in interesting ways:
running "git fetch -v --progress origin +refs/heads/*:refs/heads/*" in "/mnt/scratch0/b_used/build/slave/cache_dir/chrome--internal.googlesource.com-chrome-src--internal"
error: object file ./objects/a1/4bd89aa4cc7d7bbad7594cba0ae73e99dbb54c is empty
error: object file ./objects/a1/4bd89aa4cc7d7bbad7594cba0ae73e99dbb54c is empty
fatal: loose object a14bd89aa4cc7d7bbad7594cba0ae73e99dbb54c (stored in ./objects/a1/4bd89aa4cc7d7bbad7594cba0ae73e99dbb54c) is corrupt
fatal: The remote end hung up unexpectedly

And then the cache becomes corrupted.  This blows the cache away if this happens.

BUG=261741

Review URL: https://codereview.chromium.org/352543003

git-svn-id: fd409f4bdeea2bb50a5d34bb4d4bfc2046a5a3dd@280123 0039d316-1c4b-4281-b951-d872f2087c98

gcodetogit/depot_tools,azureplus/chromium_depot_tools,liaorubei/depot_tools,CoherentLabs/depot_tools,SuYiling/chrome_depot_tools,liaorubei/depot_tools,Chilledheart/depot_tools,fracting/depot_tools,xuyuhan/depot_tools,hsharsha/depot_tools,liaorubei/depot_tools,cpanelli/-git-clone-https-chromium.googlesource.com-chromium-tools-depot_tools,ajohnson23/depot_tools,HackFisher/depot_tools,eatbyte/depot_tools,HackFisher/depot_tools,Chilledheart/depot_tools,chinmaygarde/depot_tools,G-P-S/depot_tools,G-P-S/depot_tools,primiano/depot_tools,hsharsha/depot_tools,aleonliao/depot_tools,disigma/depot_tools,fracting/depot_tools,chinmaygarde/depot_tools,Chilledheart/depot_tools,fanjunwei/depot_tools,duongbaoduy/gtools,azureplus/chromium_depot_tools,michalliu/chromium-depot_tools,liaorubei/depot_tools,HackFisher/depot_tools,smikes/depot_tools,Midrya/chromium,disigma/depot_tools,michalliu/chromium-depot_tools,Chilledheart/depot_tools,airtimemedia/depot_tools,withtone/depot_tools,Neozaru/depot_tools,azureplus/chromium_depot_tools,sarvex/depot-tools,hsharsha/depot_tools,primiano/depot_tools,sarvex/depot-tools,Phonebooth/depot_tools,G-P-S/depot_tools,Neozaru/depot_tools,Neozaru/depot_tools,disigma/depot_tools,gcodetogit/depot_tools,eatbyte/depot_tools,yetu/repotools,xuyuhan/depot_tools,smikes/depot_tools,SuYiling/chrome_depot_tools,fanjunwei/depot_tools,Phonebooth/depot_tools,fanjunwei/depot_tools,withtone/depot_tools,withtone/depot_tools,smikes/depot_tools,Neozaru/depot_tools,aleonliao/depot_tools,duongbaoduy/gtools,xuyuhan/depot_tools,airtimemedia/depot_tools,azunite/chrome_build,npe9/depot_tools,xuyuhan/depot_tools,Phonebooth/depot_tools,michalliu/chromium-depot_tools,mlufei/depot_tools,eatbyte/depot_tools,aleonliao/depot_tools,ajohnson23/depot_tools,cpanelli/-git-clone-https-chromium.googlesource.com-chromium-tools-depot_tools,kaiix/depot_tools,gcodetogit/depot_tools,mlufei/depot_tools,airtimemedia/depot_tools,npe9/depot_tools,SuYiling/chrome_depot_tools,chinmaygarde/depot_tools,Midrya/chromium,azunite/chrome_build,G-P-S/depot_tools,sarvex/depot-tools,kaiix/depot_tools,ajohnson23/depot_tools,duongbaoduy/gtools,Midrya/chromium,duanwujie/depot_tools,CoherentLabs/depot_tools,Phonebooth/depot_tools,duanwujie/depot_tools,sarvex/depot-tools,duanwujie/depot_tools,Neozaru/depot_tools,primiano/depot_tools,npe9/depot_tools,fracting/depot_tools,airtimemedia/depot_tools,michalliu/chromium-depot_tools,yetu/repotools,mlufei/depot_tools,HackFisher/depot_tools,yetu/repotools,fanjunwei/depot_tools,smikes/depot_tools,Chilledheart/depot_tools,eatbyte/depot_tools,cpanelli/-git-clone-https-chromium.googlesource.com-chromium-tools-depot_tools,kaiix/depot_tools,azunite/chrome_build,npe9/depot_tools,smikes/depot_tools