Print detailed error message in pr-check.js if PRs are out of sync (#9545)
Print detailed error message in pr-check.js if PRs are out of sync (#9545)

A few people on the team have hit this error due to an out of sync local branch, so make the error message clear, and provide recovery steps.
shawnbuso/amphtml,shawnbuso/amphtml,cvializ/amphtml,yandex-pcode/amphtml,wjfang/amphtml,jmadler/amphtml,sharethrough/amphtml,cvializ/amphtml,zhangsu/amphtml,comScore/amphtml,clawr/amphtml,wjfang/amphtml,nexxtv/amphtml,bpaduch/amphtml,alanorozco/amphtml,jridgewell/amphtml,engtat/amphtml,zhouyx/amphtml,powdercloud/amphtml,adup-tech/amphtml,sriramkrish85/amphtml,clawr/amphtml,rajkumarsrk/amphtml,honeybadgerdontcare/amphtml,aghassemi/amphtml,luciancrasovan/amphtml,bpaduch/amphtml,engtat/amphtml,vmarteev/amphtml,aghassemi/amphtml,sebastianbenz/amphtml,arealit/amphtml,clawr/amphtml,powdercloud/amphtml,zhucl/amphtml,vmarteev/amphtml,ampproject/amphtml,yandex-pcode/amphtml,adup-tech/amphtml,donttrustthisbot/amphtml,sharethrough/amphtml,alanorozco/amphtml,camelburrito/amphtml,sklobovskaya/amphtml,voyagegroup/amphtml,sriramkrish85/amphtml,gumgum/amphtml,kmh287/amphtml,erwinmombay/amphtml,zhucl/amphtml,src-code/amphtml,yandex-pcode/amphtml,honeybadgerdontcare/amphtml,ampproject/amphtml,ampproject/amphtml,media-net/amphtml,adiant/amphtml,kixer-com/amphtml,aghassemi/amphtml,clawr/amphtml,jmadler/amphtml,sebastianbenz/amphtml,luciancrasovan/amphtml,lannka/amphtml,luciancrasovan/amphtml,yieldmo/amphtml,donttrustthisbot/amphtml,donttrustthisbot/amphtml,gumgum/amphtml,widespace-os/amphtml,jpettitt/amphtml,Gregable/amphtml,yieldbot/amphtml,adiant/amphtml,dotandads/amphtml,danielrozenberg/amphtml,donttrustthisbot/amphtml,yieldmo/amphtml,cory-work/amphtml,avimehta/amphtml,jpettitt/amphtml,zhangsu/amphtml,koshka/amphtml,sriramkrish85/amphtml,gumgum/amphtml,rajkumarsrk/amphtml,shawnbuso/amphtml,smartadserver/amphtml,camelburrito/amphtml,alanorozco/amphtml,erwinmombay/amphtml,engtat/amphtml,jpettitt/amphtml,bpaduch/amphtml,danielrozenberg/amphtml,clawr/amphtml,koshka/amphtml,danielrozenberg/amphtml,kixer-com/amphtml,arealit/amphtml,smartadserver/amphtml,camelburrito/amphtml,sharethrough/amphtml,erwinmombay/amphtml,pedjoni8/amphtml,laterpay/amphtml,jridgewell/amphtml,ampproject/amphtml,jpettitt/amphtml,camelburrito/amphtml,jmadler/amphtml,rajkumarsrk/amphtml,mhc-gh/amphtml,cvializ/amphtml,ADITION/amphtml,taboola/amphtml,zhouyx/amphtml,chaveznvg/amphtml,alanorozco/amphtml,media-net/amphtml,danielrozenberg/amphtml,gumgum/amphtml,koshka/amphtml,media-net/amphtml,rsimha-amp/amphtml,donttrustthisbot/amphtml,sharethrough/amphtml,sklobovskaya/amphtml,mhc-gh/amphtml,cory-work/amphtml,chaveznvg/amphtml,cory-work/amphtml,keithwrightbos/amphtml,lannka/amphtml,alanorozco/amphtml,koshka/amphtml,voyagegroup/amphtml,rsimha-amp/amphtml,zhucl/amphtml,sklobovskaya/amphtml,erwinmombay/amphtml,keithwrightbos/amphtml,smartadserver/amphtml,ampproject/amphtml,vmarteev/amphtml,BenDz/amphtml,kmh287/amphtml,yieldmo/amphtml,avimehta/amphtml,kixer-com/amphtml,bpaduch/amphtml,zhouyx/amphtml,Gregable/amphtml,media-net/amphtml,voyagegroup/amphtml,honeybadgerdontcare/amphtml,yandex-pcode/amphtml,mhc-gh/amphtml,cory-work/amphtml,mhc-gh/amphtml,cvializ/amphtml,taboola/amphtml,honeybadgerdontcare/amphtml,kamtschatka/amphtml,danielrozenberg/amphtml,chaveznvg/amphtml,techhtml/amphtml,lannka/amphtml,prateekbh/amphtml,shawnbuso/amphtml,kixer-com/amphtml,laterpay/amphtml,laterpay/amphtml,laterpay/amphtml,tlong2/amphtml,jpettitt/amphtml,sebastianbenz/amphtml,comScore/amphtml,mhc-gh/amphtml,BenDz/amphtml,voyagegroup/amphtml,aghassemi/amphtml,prateekbh/amphtml,rajkumarsrk/amphtml,yieldbot/amphtml,voyagegroup/amphtml,jmadler/amphtml,src-code/amphtml,widespace-os/amphtml,yieldbot/amphtml,jridgewell/amphtml,techhtml/amphtml,comScore/amphtml,chaveznvg/amphtml,zhucl/amphtml,yandex-pcode/amphtml,tlong2/amphtml,nexxtv/amphtml,kmh287/amphtml,zhouyx/amphtml,prateekbh/amphtml,chaveznvg/amphtml,erwinmombay/amphtml,koshka/amphtml,adiant/amphtml,cory-work/amphtml,wjfang/amphtml,sebastianbenz/amphtml,ADITION/amphtml,prateekbh/amphtml,taboola/amphtml,sharethrough/amphtml,mhc-gh/amphtml,pedjoni8/amphtml,luciancrasovan/amphtml,arealit/amphtml,camelburrito/amphtml,prateekbh/amphtml,ADITION/amphtml,media-net/amphtml,chaveznvg/amphtml,aghassemi/amphtml,camelburrito/amphtml,clawr/amphtml,adiant/amphtml,shawnbuso/amphtml,adup-tech/amphtml,zhouyx/amphtml,engtat/amphtml,bpaduch/amphtml,keithwrightbos/amphtml,kmh287/amphtml,bpaduch/amphtml,keithwrightbos/amphtml,vmarteev/amphtml,Gregable/amphtml,laterpay/amphtml,voyagegroup/amphtml,sriramkrish85/amphtml,src-code/amphtml,nexxtv/amphtml,sklobovskaya/amphtml,avimehta/amphtml,pedjoni8/amphtml,arealit/amphtml,ampproject/amphtml,yieldmo/amphtml,nexxtv/amphtml,ampproject/amphtml,danielrozenberg/amphtml,lannka/amphtml,prateekbh/amphtml,vmarteev/amphtml,keithwrightbos/amphtml,ADITION/amphtml,sharethrough/amphtml,voyagegroup/amphtml,donttrustthisbot/amphtml,honeybadgerdontcare/amphtml,nexxtv/amphtml,adiant/amphtml,jmadler/amphtml,taboola/amphtml,rajkumarsrk/amphtml,luciancrasovan/amphtml,kixer-com/amphtml,widespace-os/amphtml,src-code/amphtml,widespace-os/amphtml,widespace-os/amphtml,jmadler/amphtml,avimehta/amphtml,kmh287/amphtml,luciancrasovan/amphtml,dotandads/amphtml,avimehta/amphtml,keithwrightbos/amphtml,media-net/amphtml,rajkumarsrk/amphtml,laterpay/amphtml,tlong2/amphtml,engtat/amphtml,sebastianbenz/amphtml,ampproject/amphtml,widespace-os/amphtml,comScore/amphtml,techhtml/amphtml,vmarteev/amphtml,yieldmo/amphtml,adiant/amphtml,techhtml/amphtml,adup-tech/amphtml,arealit/amphtml,taboola/amphtml,rsimha-amp/amphtml,honeybadgerdontcare/amphtml,kamtschatka/amphtml,smartadserver/amphtml,yieldbot/amphtml,adup-tech/amphtml,kmh287/amphtml,zhucl/amphtml,rsimha-amp/amphtml,yieldbot/amphtml,zhouyx/amphtml,yandex-pcode/amphtml,jridgewell/amphtml,zhangsu/amphtml,cvializ/amphtml,arealit/amphtml,dotandads/amphtml,Gregable/amphtml,lannka/amphtml,wjfang/amphtml,kixer-com/amphtml,zhangsu/amphtml,smartadserver/amphtml,Gregable/amphtml,adiant/amphtml,powdercloud/amphtml,Gregable/amphtml,alanorozco/amphtml,cory-work/amphtml,donttrustthisbot/amphtml,yieldmo/amphtml,mhc-gh/amphtml,BenDz/amphtml,yieldmo/amphtml,vmarteev/amphtml,gumgum/amphtml,arealit/amphtml,jridgewell/amphtml,jpettitt/amphtml,comScore/amphtml,yandex-pcode/amphtml,sklobovskaya/amphtml,wjfang/amphtml,powdercloud/amphtml,kixer-com/amphtml,koshka/amphtml,rsimha-amp/amphtml,techhtml/amphtml,zhangsu/amphtml,alanorozco/amphtml,tlong2/amphtml,wjfang/amphtml,aghassemi/amphtml,smartadserver/amphtml,sebastianbenz/amphtml,pedjoni8/amphtml,jpettitt/amphtml,sklobovskaya/amphtml,kamtschatka/amphtml,nexxtv/amphtml,prateekbh/amphtml,engtat/amphtml,shawnbuso/amphtml,cory-work/amphtml,media-net/amphtml,luciancrasovan/amphtml,BenDz/amphtml,jpettitt/amphtml,yieldbot/amphtml,wjfang/amphtml,src-code/amphtml,BenDz/amphtml,dotandads/amphtml,jridgewell/amphtml,alanorozco/amphtml,tlong2/amphtml,erwinmombay/amphtml,pedjoni8/amphtml,techhtml/amphtml,src-code/amphtml,powdercloud/amphtml,zhangsu/amphtml,comScore/amphtml,rsimha-amp/amphtml,camelburrito/amphtml,rajkumarsrk/amphtml,tlong2/amphtml,Gregable/amphtml,lannka/amphtml,sriramkrish85/amphtml,gumgum/amphtml,danielrozenberg/amphtml,cvializ/amphtml,nexxtv/amphtml,comScore/amphtml,jridgewell/amphtml,avimehta/amphtml,kamtschatka/amphtml,kamtschatka/amphtml,kamtschatka/amphtml,sriramkrish85/amphtml,zhucl/amphtml,taboola/amphtml,clawr/amphtml,lannka/amphtml,rsimha-amp/amphtml,honeybadgerdontcare/amphtml,powdercloud/amphtml,danielrozenberg/amphtml,Gregable/amphtml,zhouyx/amphtml,bpaduch/amphtml,BenDz/amphtml,dotandads/amphtml,sklobovskaya/amphtml,mhc-gh/amphtml,zhucl/amphtml,keithwrightbos/amphtml,taboola/amphtml,adup-tech/amphtml,engtat/amphtml,pedjoni8/amphtml,powdercloud/amphtml,media-net/amphtml,dotandads/amphtml,shawnbuso/amphtml,gumgum/amphtml,ADITION/amphtml