Abort if no subcommand.
Abort if no subcommand.

Fixes #3412

nasht00/jekyll,gencer/jekyll,pmarsceill/jekyll,codeclimate-testing/jekyll,pmarsceill/jekyll,ducktyper/jekyll,Kinghack/kinghack.github.com,derekgottlieb/jekyll,chrisfinazzo/jekyll,codeclimate-testing/jekyll,kuangyeheng/jekyll,aarvay/jekyll,bsmr-ruby/jekyll,jaybe-jekyll/jekyll,ZDroid/jekyll,bsmr-ruby/jekyll,xiebinhqy/jklly_china,Teino1978-Corp/jekyll,ducktyper/jekyll,nasht00/jekyll,LeuisKen/jekyllcn,sasongkojati/jekyll,rlugojr/jekyll,stomar/jekyll,howkj1/jekyll,Teino1978-Corp/Teino1978-Corp-jekyll,thetaxman/jekyll,nasht00/jekyll,jekyll/jekyll,tomjohnson1492/jekyll,xiebinhqy/jklly_china,tillgrallert/jekyll,PepSalehi/jekyll,nasht00/jekyll,thetaxman/jekyll,rebornix/jekyll,mrb/jekyll,MauroMrod/jekyll,yihangho/jekyll,kuangyeheng/jekyll,noikiy/jekyll,chrisfinazzo/jekyll,larryfox/jekyll,stomar/jekyll,aarvay/jekyll,Teino1978-Corp/Teino1978-Corp-jekyll,xcatliu/jekyllcn,rebornix/jekyll,sanxore/sanxore.github.com,anthonyrosengren/grasshoppergathering2.github-io,rasa2011/rasa2011.github.io,getandpost/jekyll.github.io,likong/jekyll,Teino1978-Corp/jekyll,jeffkole/jekyll,zsyed91/jekyll,Strangehill/jekyll,gencer/jekyll,aarvay/jekyll,ZDroid/jekyll,PepSalehi/jekyll,nickg33/jekyll,larryfox/jekyll,codeclimate-testing/jekyll,Strangehill/jekyll,chrisfinazzo/jekyll,jaybe-jekyll/jekyll,tillgrallert/jekyll,darwin/jekyll,xcatliu/jekyllcn,xcatliu/jekyllcn,mrb/jekyll,CPVPLachlan/CPVP-Blog,princeofdarkness76/jekyll,sanxore/sanxore.github.com,alfredxing/jekyll,ryanshaw/jekyll,sanxore/sanxore.github.com,CPVPLachlan/CPVP-Blog,alex-kovac/jekyll,rebornix/jekyll,jekyll/jekyll,rasa2011/rasa2011.github.io,LeuisKen/jekyllcn,noikiy/jekyll,likong/jekyll,tomjohnson1492/jekyll,gencer/jekyll,jeffkole/jekyll,ryanshaw/jekyll,zsyed91/jekyll,darwin/jekyll,superve/jekyll,Strangehill/jekyll,noikiy/jekyll,gaosboy/jekyll,hartmel/jekyll,dansef/jekyll,princeofdarkness76/jekyll,tomjohnson1492/jekyll,derekgottlieb/jekyll,x-way/jekyll,mrb/jekyll,bsmr-ruby/jekyll,x-way/jekyll,tillgrallert/jekyll,zsyed91/jekyll,LeuisKen/jekyllcn,ajhit406/jekyll,gencer/jekyll,alex-kovac/jekyll,alfredxing/jekyll,sasongkojati/jekyll,superve/jekyll,FlyingWHR/jekyll,ryanshaw/jekyll,getandpost/jekyll.github.io,pmarsceill/jekyll,Teino1978-Corp/Teino1978-Corp-jekyll,floydpraveen/jekyll,jaybe-jekyll/jekyll,brint/jekyll,stomar/jekyll,jmepg/jekyll,xiebinhqy/jklly_china,gencer/jekyll,brint/jekyll,fulldecent/jekyll,brint/jekyll,Strangehill/jekyll,floydpraveen/jekyll,yihangho/jekyll,dansef/jekyll,anthonyrosengren/grasshoppergathering2.github-io,jaybe-jekyll/jekyll,brint/jekyll,superve/jekyll,jmepg/jekyll,tillgrallert/jekyll,Kinghack/kinghack.github.com,princeofdarkness76/jekyll,Strangehill/jekyll,nickg33/jekyll,jekyll/jekyll,ajhit406/jekyll,noikiy/jekyll,dansef/jekyll,howkj1/jekyll,hartmel/jekyll,xcatliu/jekyllcn,stomar/jekyll,alex-kovac/jekyll,zsyed91/jekyll,FlyingWHR/jekyll,jekyll/jekyll,bsmr-ruby/jekyll,xiebinhqy/jklly_china,gaosboy/jekyll,PepSalehi/jekyll,ducktyper/jekyll,rlugojr/jekyll,larryfox/jekyll,jeffkole/jekyll,sasongkojati/jekyll,FlyingWHR/jekyll,fulldecent/jekyll,tillgrallert/jekyll,CPVPLachlan/CPVP-Blog,x-way/jekyll,alex-kovac/jekyll,ajhit406/jekyll,anthonyrosengren/grasshoppergathering2.github-io,rasa2011/rasa2011.github.io,ajhit406/jekyll,x-way/jekyll,derekgottlieb/jekyll,alfredxing/jekyll,fulldecent/jekyll,tomjohnson1492/jekyll,yhironaka/yhironaka.github.io,kuangyeheng/jekyll,chrisfinazzo/jekyll,thetaxman/jekyll,darwin/jekyll,jeffkole/jekyll,ryanshaw/jekyll,pmarsceill/jekyll,alfredxing/jekyll,alex-kovac/jekyll,fulldecent/jekyll,gaosboy/jekyll,rlugojr/jekyll,derekgottlieb/jekyll,tomjohnson1492/jekyll,jmepg/jekyll,floydpraveen/jekyll,MauroMrod/jekyll,Kinghack/kinghack.github.com,yihangho/jekyll,getandpost/jekyll.github.io,MauroMrod/jekyll,rlugojr/jekyll,howkj1/jekyll,mrb/jekyll,ZDroid/jekyll,darwin/jekyll,princeofdarkness76/jekyll,Teino1978-Corp/jekyll,hartmel/jekyll,likong/jekyll,floydpraveen/jekyll,nickg33/jekyll