Chanot branch[0].isdigit()nging --milestone to use JSON source and adding prompt for branch mismatch.
Chanot branch[0].isdigit()nging --milestone to use JSON source and adding prompt for branch mismatch.

Sample output:

$ drover --merge 196360 --milestone 27

Not all platforms have same branch number for M27.

Here's a list of platforms on each branch:
-(1453): win, ios, cf, mac, linux, android
-(1460): cros
Which branch? ('q' to cancel) 1453

Review URL: https://chromiumcodereview.appspot.com/14544004

git-svn-id: fd409f4bdeea2bb50a5d34bb4d4bfc2046a5a3dd@198282 0039d316-1c4b-4281-b951-d872f2087c98

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