Don't update git url if 'read' times out
Don't update git url if 'read' times out

Previous code checked the exit status of 'echo' instead of 'read' to
determine if the 'read' command had timed out.

TEST=Create a mirror of depot_tools.git, git clone it, then run
./update_depot_tools, see prompt for changing the URL, wait at
least 60 seconds and verify that you get the timeout message.

R=maruel@chromium.org
BUG=

Review URL: https://codereview.chromium.org/25110004

git-svn-id: fd409f4bdeea2bb50a5d34bb4d4bfc2046a5a3dd@227427 0039d316-1c4b-4281-b951-d872f2087c98

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